Post by: Momentus on 11/08/2023 16:01:52
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Dark Motion
The diagram shows a blue ball traveling at a velocity of A-C, which is struck by a red ball traveling at a velocity of B-C.
The Blue ball is deflected with a resultant velocity C-D, the vector change is solely of direction, the red ball comes to rest its vector change is solely of magnitude.
That is all there is to see. A diagram that illustrates Newton?s equal and opposite force and momentum change. X is the difference between the orthodox view and reality.
That is the simple part, describing Dark Motion.
Newton's laws of motion have served as the foundation for the development of further concepts, including those of symmetry and reversibility in physics, which are considered to be inviolate.
Dark Motion is neither symmetrical nor reversible. The diagram clearly shows this.
That is the discovery. Now for some speculation
Dark Motion is a natural phenomenon therefore it should appear in nature. Dark matter and dark energy are two examples where Dark Motion provides plausible solutions. It also offers tantalising glimpses of a unified theory by moving classical theory closer to quantum mechanics.
A practical use for an engineered version would be an Internally Reacted Thruster. A device that exerts constant force in one direction.
An IRT would consist of a motor and the reacting parts and would produce thrust proportional to the mass of the active elements and operation speed.
An important characteristic of the IRT stems from the fact that work done is force over distance, If the IRT does not move a load then it does not consume any power. For instance, hovering would only consume ?no load? power.
Fit an IRT in place of wheels to give vectored thrust for a flying car
Replace the rocket in a spaceship, take the wings off planes and replace the fuel hungry jet engines with electric motors. Float ocean cargo vessels over land, Cruise ships to the Grand Canyon. Every city could have an overhead platform for emergency vehicles and communication aerials.
No doubt you will think of your own applications Skiing? Sailing? Gliding?
One final thought, lifting massive loads. The IRT would act like a hydraulic jack, just lifting the load off the ground. Effectively that is anti-gravity. As the earth is rotating, the fully equipped orbital station would not be held on the surface by gravity, just held in place by the IRTs until the earth rotated away. Like a slingshot.
I originally wrote this for my Grandchildren.
I am quite jealous to think that when you are Grandparents all this will be mundane and uses of Dark Motion that I cannot imagine will be commonplace.
Your loving Grandfather, Brian.
The twin pendulum model that you played with many years ago is just a convenient way of demonstrating this.
Post by: Bored chemist on 11/08/2023 16:14:51
If the blue ball is moving right to left and hits the red ball then it will impart some momentum in that direction to the red ball.
so teh red ball will not be left stationary..
Also
the red ball comes to rest its vector change is solely of magnitude.That depends on your point of view.
Post by: Momentus on 11/08/2023 16:41:19
Post by: Origin on 11/08/2023 16:41:56
That is all there is to see. A diagram that illustrates Newton?s equal and opposite force and momentum change. X is the difference between the orthodox view and reality.I think the difference exists because you drew the diagram incorrectly.
Do you have any mathematics to back up why you drew the diagram the way you did? I can draw a diagram that violates physics easily that does not mean the diagram is correct.
Post by: Origin on 11/08/2023 16:43:50
In Snooker it is called a kiss, when both balls are moving. Do try it. Roll a blue ball down the table and hit it with a cue ball at right angles to its line of motion. JFD, I have and, with a bit of patience, you will hit the sweet spot.I have never seen a billiard ball violate physics.
Post by: Momentus on 11/08/2023 16:56:21
The forces are equal and opposite, the momentum exchange is equal and opposite.
Post by: Bored chemist on 11/08/2023 17:46:04
In Snooker it is called a kiss, when both balls are moving. Do try it. Roll a blue ball down the table and hit it with a cue ball at right angles to its line of motion. JFD, I have and, with a bit of patience, you will hit the sweet spot.I have played enough pool to know that you can only do it because of the nap on the table.
Without that, what you have posted is simply wrong- for the reason I gave
You are misrepresenting physics.
Just because I can draw a free body diagram of an elephant taking off, that doesn't mean elephants can fly
Post by: Origin on 11/08/2023 18:14:11
I need help here. Please show me the correct mathematics.The correct mathematics are found in Newtonian physics. I'm not really sure what your diagram is all about, nothing is labeled. The thing is you have a line going where you say the ball 'should' go and a line where you say the ball really goes. There is no math and no explanation of how there is any deviation of the ball from what physics would predict, all we have is you claiming it does.
Post by: Origin on 11/08/2023 18:41:38
This is a discovery I made many years ago.It would help greatly if you stated up front what your discovery is.
The diagram shows a blue ball traveling at a velocity of A-CA-C is not a velocity, it is a direction. So what we have is a blue ball moving at an unknown speed in a certain direction.
which is struck by a red ball traveling at a velocity of B-C.Again B-C is not a velocity, it is a direction. So what we have is a red ball moving at an unknown speed in a certain direction.
The Blue ball is deflected with a resultant velocity C-D, the vector change is solely of direction, the red ball comes to rest its vector change is solely of magnitude.There is not enough information given to have any idea where the balls would end up. We do not know the speed of either ball nor do we know at what angle the balls hit each other.
Post by: Momentus on 12/08/2023 13:41:09
There is not enough information given to have any idea where the balls would end up. We do not know the speed of either ball nor do we know at what angle the balls hit each other.My mistake. I made the assumption that vector diagrams were commonplace and that anyone who would be contributing to the thread would recognise that at a velocity of A-C was referencing a vector diagram.
The diagram is drawn to scale. AC is 4 units long, BC is 3 units long, and therefore CX is 5 units long the vector sum of AC, BC. That is what you believe to be true, as it preserves symmetry and is reversible.
However Newton says otherwise. In the Principia he shows, at length, that a force applied at right angles to the direction of travel results in a change of direction and not, repeat for emphasis, not a change of speed. This forms the basis for his centripetal force concept and onwards to gravity.
When red strikes blue the forces generated are equal and opposite, bringing red to rest, and changing the direction of blue, but crucially not the speed. Thus the position of blue is determined by the construction of a triangle with a vertical side of length BC and hypotenuse of length AC The positions as shown.
Post by: Origin on 12/08/2023 14:25:40
My mistake. I made the assumption that vector diagrams were commonplace and that anyone who would be contributing to the thread would recognise that at a velocity of A-C was referencing a vector diagram.If you had the information on the graph it might make sense. If you show a chart with no labels on the axis how are we to know what you are talking about?
The diagram is drawn to scale. AC is 4 units long, BC is 3 units long, and therefore CX is 5 units long the vector sum of AC, BCBased on your unclear drawing there is no possible way the the blue ball would end up moving in the direction indicated.
I assume this is about an elastic collision, since you did not specify. Could you show you work using the elastic collision formula so we can get a better idea of what you are trying to prove? The picture you supplied is completely useless in trying to analyze the situation.
Post by: Momentus on 13/08/2023 18:57:54
In the first law, an object will not change its motion unless a force acts on it. In the second law, the force on an object is equal to its mass times its acceleration. In the third law, when two objects interact, they apply forces to each other of equal magnitude and opposite direction.
Consider two masses, bodies, particles, ball bearings, billiard balls golf balls, one is red one is blue. For convenience we say that they have the same mass.
With reference to the drawing the vector of the red mass is shown as BC, with a speed of 3 units. The blue mass is moving as shown by AC with a speed of 4 units.
Their paths interact as shown such that the red ball is subjected to a force, directly opposed to (BC) its line of action, which changes its speed of velocity. There is no force acting at an angle to BC, there will be no change of direction
The same force acts on the blue ball at right angles to its line of action, deflecting it. and changing its direction of velocity. There is no force acting along the line of action (AC) of the blue mass, therefore there is no change in the speed of the blue mass.
Straightforward Newton. Since the same force is acting on both masses, there will be equal changes in momentum.
That change is shown in the diagram as the red mass coming to rest, no residual momentum, the blue mass moves on the line of CD an unchanged speed of 4 units and also along the line of BC at speed of 3 units.
First law, check.
Second law check.
Third law check.
Quote
bringing red to rest, and changing the direction of blue, but crucially not the speed.
Again, that violates all the laws. It's trivially falsified with an actual experiment instead of bogus non-mathematical assertions.
Like I said before I need help with this. If you are demanding a mathematical proof, then please show me what the mathematical description of this two mass collision should look like.
If the trivial experiment which you refer to is
I did this experiment in school, and your assertions have been falsified.How did you measure the increase in speed of the blue mass. Please believe me when I say I really am interested in that fact as I have never ever observed it myself in the many experiments I have carried out over the years.
Post by: paul cotter on 13/08/2023 20:16:11
Post by: Origin on 13/08/2023 23:21:22
That change is shown in the diagram as the red mass coming to rest, no residual momentum, the blue mass moves on the line of CD an unchanged speed of 4 units and also along the line of BC at speed of 3 units.OK.
bringing red to rest, and changing the direction of blue, but crucially not the speed.You just said the speed did change! The blue ball was moving originally at 4 units in the CD (x) direction. After the collision it is moving those 4 units plus 3 units in the BC (y) direction. That is an increase in speed.
Post by: Bored chemist on 13/08/2023 23:25:38
In the first law, an object will not change its motion unless a force acts on it.And an object will change its motion if a force acts on it.
What you say is the red ball stops because it experiences a force from the blue ball.
And that requires that the two are (momentarily) in contact.
But, at the moment when they are in contact, the blue ball is moving right to left.
The red ball is in contact with a thing moving right to left.
So there's a force on it from right to left.
So there's a change in motion of the red ball from right to left
Since the initial component of its motion in that direction is zero, and there's a change in that motion, the final motion must include a component in the horizontal direction.
So it can not be stationary after the collision.
Why does the blue ball not push the red ball right to left?
How does it know that it's only allowed to push it up (to arrest that component of its motion) but not from right to left?
Post by: Momentus on 14/08/2023 14:00:36
I can't make any sense of the diagram suppliedI am sorry that you are unable to make sense of my diagram.
Perhaps you with your knowledge of vectors could describe what happens when masses collide at right angles?
Post by: Momentus on 14/08/2023 14:30:30
You just said the speed did change! The blue ball was moving originally at 4 units in the CD (x) direction. After the collision it is moving those 4 units plus 3 units in the BC (y) direction. That is an increase in speed.The momentum of the blue ball is changed by its change in direction, not by a change in speed. The change in momentum of the blue ball is equal to the change in momentum of the red ball. Newton again. To accommodate this change the blue ball moves, at its original speed but at an angle such that gives motion in the y direction of three units. As drawn.
Post by: Origin on 14/08/2023 14:49:52
The momentum of the blue ball is changed by its change in direction, not by a change in speed.You keep saying that but your numbers say otherwise! You appear to be arguing with yourself.
Before the collision the blue ball is moving at 4 unit in the x direction. After the collision the blue ball is moving at 4 units in the x direction and 3 units in the y direction. That means the blue ball is moving away from the point of the collision at 5 units.
How can you say the blue ball did not change its speed? You prove that it did change speed with the math and then you turn around and say it didn't change speed - very strange.
Post by: Momentus on 14/08/2023 14:52:29
Why does the blue ball not push the red ball right to left?
How does it know that it's only allowed to push it up (to arrest that component of its motion) but not from right to left?
I think if you google "line of action of force? or similar you will find an explanation.
If you do the experiment you will see for yourself. Timing is difficult, if the red ball impacts too early, it strikes the front of the blue ball. This slows the blue ball down and the red ball is deflected forward. If the red ball hits too late, on the back of the blue ball, it speeds the blue ball up and is deflected to the rear.
If you hit the blue ball centrally, it neither slows down nor speeds, up and the red ball is not deflected forwards or backwards. It stops.
Post by: Origin on 14/08/2023 15:05:33
If you hit the blue ball centrally, it neither slows down nor speeds, upNot according to Newton and not according to your analysis!?! Do you seriously think that 4 units = 5 units?
You are not making any sense.
Post by: Momentus on 14/08/2023 15:29:05
How can you say the blue ball did not change its speed?Yes I see your point. If this was a simple vector sum then it would be just as you describe.
It is not a simple vector sum. The collision is governed by Newton's laws.
Momentum is vm, velocity x mass. Velocity is a vector quantity of speed and direction.
To change momentum by changing speed, force is directed along the line of motion.
To change momentum by changing direction, force is directed at right angles to the line of motion.
Before the collision the ball is moving at 4 units in the x direction The force applied in the y direction changes the direction. All the force is reacted by the change in direction. The force required to change the speed of the red ball is reacted by the force required to change the direction of the blue ball. The speed of the blue ball does not change.
After the collision the blue ball is moving at the same speed, but in a different direction. That new direction is determined by the equal and opposite change in momentum of the two balls.
The red ball?s change in momentum is due to a change in speed. The blue balls change in momentum. Is due to a change in direction.
Equal and opposite forces, equal and opposite momentum change.
Post by: Bored chemist on 14/08/2023 16:36:02
Timing is difficult, if the red ball impacts too early, it strikes the front of the blue ball. This slows the blue ball down and the red ball is deflected forward. If the red ball hits too late, on the back of the blue ball, it speeds the blue ball up and is deflected to the rear.
If you hit the blue ball centrally, it neither slows down nor speeds, up and the red ball is not deflected forwards or backwards. It stops.
And how good do you have to get the timing?
What is the difference between something that does not happen, and something that can only happen if you do something impossible?
Post by: Origin on 14/08/2023 17:35:28
Yes I see your point.Apparently not.
If this was a simple vector sum then it would be just as you describe.
It is not a simple vector sum. The collision is governed by Newton's laws.
It's not a vector sum? Really? So you prefer to say that the ball is moving in 2 directions at the same time??
In essence you say, "Here is the math that says the speed of the blue ball increases after the collision; but just ignore that".
That is a really damn odd way to try and make a point.
edited to remove an unnecessary insult.
Post by: Momentus on 16/08/2023 15:34:35
Here is the math that says the speed of the blue ball increasesI keep asking for some maths to show how you think that the collision works out.
I ask because I do not know how to show it mathematically.
That really does make it damn peculiar. Show the math that you refer to. please. it would really help me to understand why you have a problem with centripetal force.
Post by: Momentus on 16/08/2023 16:11:08
I think that this applies to a blue ball rolling down a snooker table and struck by a red ball rolling across the table
Also, the red ball stops at the point of impact.
I cannot see how it can behave in any other way, but seek confirmation.
Post by: paul cotter on 16/08/2023 16:13:47
Post by: Momentus on 16/08/2023 16:50:22
It's over 50years since I did this stuff and since I never had need to use it, I can't remember exactly. I think you look at the conditions at impact and take components of momentum and put mv=m1v1 for both components and solve.Anyone? is that enough of a lead?
Post by: Bored chemist on 16/08/2023 17:35:54
If a force is applied perpendicular to an object's velocity, it will alter the direction of motion without changing the speed.OK
Consider the earth orbiting the sun (In a circle- just to make the maths easier..
The gravitational force is perpendicular to the movement of the earth.
Now imagine that we suddenly make the sun heavier or lighter.
What will happen to the motion of the earth?
Do you really think it will carry on along at the same speed?
Post by: Halc on 16/08/2023 17:58:13
OK, this was sort of a question, not much of an assertion, but if it turns into one, you're trolling.
If a force is applied perpendicular to an object's velocity, it will alter the direction of motion without changing the speed.Quick experiment will falsify this.
I think that this applies to a blue ball rolling down a snooker table and struck by a red ball rolling across the table
I lay a toy train track running to the south, between my legs, and one car has a golf tee on it. Train moves at 0.1 meters per second south. I straddle the track, armed with my favorite driver. When the ball comes into optimal position, I give it a tremendous westward whack, what you are calling a force perpendicular to the object's southbound velocity. By your assertions, the ball will attain a new velocity of 0.1 m/sec mostly west and will only make it past the edge of the track because it's falling off the tee and not go 200 meters.
Back to your topic: Kindly compute the force between the two balls. If you cannot do that, then learn some physics and stop asserting nonsense.
Post by: Momentus on 16/08/2023 18:10:55
Do you really think it will carry on along at the same speed?
Please point out the difference between rpm and tangential speed. Try the skater example. Please, this is a science forum.
Post by: alancalverd on 16/08/2023 18:31:24
Post by: Origin on 16/08/2023 18:39:21
I keep asking for some maths to show how you think that the collision works out.How can you possibly think you know what happens after a collision if you can't properly analyze it?
Here is how you would calculate the final speed of the blue ball based on your results.
I don't like using the term 'units' for velocity, so let's use furlongs per fortnight. Just kidding let's use m/s.
According to you after the collision the velocity in the x direction is 4 m/s and the velocity in the y direction is 3 m/s.
The formula to find the length (speed) of the line is: square root {x^2 + y^2}.
The final speed of the blue ball according to your analysis is: square root {x^4 + y^3} = 5 m/s.
Post by: Momentus on 16/08/2023 18:59:13
consider the collision of two ideal perfectly elastic projectilesYes. do that please. Give an answer. The question is what happens according to Newton's laws?
I get a lot of good advice as to what I need to do. What happens when two perfect bodies collide? If you know, share it, for the sake of whatever deity you hold dear.
Post by: Momentus on 16/08/2023 19:11:14
By your assertions, the ball will attain a new velocity of 0.1 m/sec mostly west and will only make it past the edge of the track because it's falling off the tee and not go 200 meters.Excellent challenge. I do not have an answer. That is why I have asked the question. It could be that it is not only the mv of the club head that is involved, but your magnificent biceps changing the nature of the impact, only a guess.
Post by: Bored chemist on 16/08/2023 23:11:57
Please point out the difference between rpm and tangential speed.They have different units.
Please answer my question.
Do you really thing that, for example, doubling the mass of the sun would not affect the orbital speed of the earth?
Post by: Origin on 16/08/2023 23:34:07
Yes. do that please. Give an answer. The question is what happens according to Newton's laws?I agree with your results and the are perfectly in line with Newtons laws.
I get a lot of good advice as to what I need to do. What happens when two perfect bodies collide? If you know, share it, for the sake of whatever deity you hold dear.
The blue ball is moving along the x-axis at 4 m/s and the red ball is moving along the y-axis at 3 m/s. The collision occurs in such a way that the impact is on top of the blue ball, so the momentum transfer is in the y direction. Assuming a instantaneous perfectly elastic collision on the y axis the momentum of the red ball would be transferred to the blue ball. This will result in the red ball stopping and the blue ball moving in the y direction at 3 m/s. The blue ball will continue to move in the x direction at 4 m/s. The resultant speed of the blue ball will be 5 m/s.
Post by: paul cotter on 17/08/2023 10:42:42
Post by: Momentus on 17/08/2023 12:51:43
The blue ball will continue to move in the x direction at 4 m/s.
Isaac NEWTON: Philosophiae Naturalis Principia Mathematica. 3rd Ed.
Book I Section II.
Translated and Annotated by Ian Bruce. Page 95
SECTION II. On the finding of centripetal forces.
PROPOSITION I. THEOREM I.
Truly, when the body comes to B, by a single but large impulse the centripetal force acts, and brings about that the body deflects from the line Bc and goes along in the line BC ; cC is acting parallel to BS itself, crossing BC in C; and with the second part of the time completed, the body (by the corollary to Law I.) may be found at C
Newton Centripetal.png (25.16 kB . 221x219 - viewed 270 times)If you apply the same iterations to my original diagram you obtain the same result as shown in Newton's drawing. the blue ball maintains its original speed.
An impulse changes the direction, it does not change the speed, not in Newton's derivation of centripetal force nor in my simple diagram.
Post by: Momentus on 17/08/2023 13:16:07
doubling the mass of the sun would not affect the orbital speed of the earth?
Newton Centripetal 2.png (4.41 kB . 154x78 - viewed 234 times)Double F, halve r Tangential velocity remains constant. If you mean that orbital speed is the time for one orbit, then yes the revs would speed up.
Post by: Origin on 17/08/2023 15:07:13
If you apply the same iterations to my original diagram you obtain the same result as shown in Newton's drawing. the blue ball maintains its original speed.Only the x component of the speed is constant.
An impulse changes the direction, it does not change the speed, not in Newton's derivation of centripetal force nor in my simple diagram.Wrong. Your diagram shows that after the collision the blue ball acquires an additional velocity of 3 m/s in the y direction. This results in the blue ball increasing it's overall speed to 5 m/s at an angle of 36.9 degrees from the x axis.
This is all in line with Newtonian laws.
So once again I will point out that you got the right answer but for some reason you refuse to accept your own answer! Your attitude is really strange.
Maybe an example will help understand.
If I drive my car in a straight line for 1 hour and I were to tell you that I ended up being 30 miles north and 40 miles west of my starting point how far away from my starting point would I be? I would be 50 miles from my starting position. IOW my y speed would be 30 mph and my x speed would be 40 mph and the speed along my line of travel would be 50 mph. Hope that helps.
Post by: Momentus on 17/08/2023 16:19:19
In my diagram I apply a force at right angles to the line AC.
Newton deflects to line BC. In his drawing, AB & BC are the same length indicating that the speed is unchanged.
In my drawing there is a deflection to the line CD. AC a & CD are the same length indication that the speed is unchanged.
Newton makes it quite clear that even with repeated impulses applied at right angles to the direction, the speed remains unchanged. Thus he shows that his centripetal force causes a body to orbit at constant speed.
The blue ball does not increase its speed to 5 units. The large impulse does not change the speed. It does not do it in Newton?s drawing, it does not do it in my drawing.
So once again I will point out that you got the right answer but for some reason you refuse to accept your own answer! Your attitude is really strange.
My answer is now and always has been, from the start that the blue ball does not change speed. It moves at 4 units before and after the collision. My drawing shows that AC a & CD are the same length and represent the same speed.
In Newton?s drawing, AB & BC are the same length representing the same speed.
When the blue ball is subjected to repeated collisions, orbits at constant speed. Just like Newton?s drawing
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Post by: Bored chemist on 17/08/2023 16:30:48
It is not a simple vector sum.Why not?
Post by: Momentus on 17/08/2023 16:32:17
If I drive my car in a straight lineIf I drive for 4 miles turn 48 Degrees and drive for 4 miles will have traced the path of the blue ball. It would have no bearing on the discussion.
You cannot accelerate( increase speed) a mass by applying force at right angles to its line of action. You can only accelerate a mass by applying a force along its line of action.
Post by: Momentus on 17/08/2023 16:36:20
Why not?Ask sir Issac. Read his book. Study centripetal force. Look at the drawing. You cannot accelerate a mass by pushing at right angles to its motion. therefore you cannot accelerate the blue ball from 4 to 5. It is not a vector sum
Post by: paul cotter on 17/08/2023 17:18:41
Post by: Bored chemist on 17/08/2023 17:46:48
You cannot accelerate a mass by pushing at right angles to its motion.You can.
That's what the tension does if you swing something round on a string.
Post by: Origin on 17/08/2023 18:05:08
You cannot accelerate a mass by applying force at right angles to its line of action.That is not true according to physics or even according to you!
You showed that before the collision the blue balls movement in the y direction was zero and after the collision the blue balls speed was 3 m/s in the y direction. That obviously means the blue ball accelerated from 0 to 3 m/s.
You continue to argue with yourself! This is really weird. Are you by chance using dark logic? ;)
Post by: Origin on 17/08/2023 19:03:16
My answer is now and always has been, from the start that the blue ball does not change speed. It moves at 4 units before and after the collision.Wrong, you said this:
the blue mass moves on the line of CD an unchanged speed of 4 units and also along the line of BC at speed of 3 units.That means the blue ball is moving 4 units in the x direction and 3 units in the y direction which means the ball is moving at 5 units along a line that is 36.9 degrees from the CD line (x-axis).
So it seems the source of your confusion is that you do not realize that before the collision the blue ball is moving at 4 units along the line of travel and after the collision the blue ball is moving at 5 units along the new line of travel, even though the math clearly shows that.
Think about it for a second before you say no.
Post by: Momentus on 18/08/2023 11:28:05
Changes the velocity of a moving mass
By changing the direction of the mass.
It is also known as centripetal force.
The earth is subjected to a centripetal force as its velocity constantly changes in orbit around the sun.
Mass subjected to a perpendicular force, be it the large impulse that Newton refers to, or the continuos force of gravity keeping the earth in orbit, does not increase the speed of the mass.
The only force acting on the moving blue mass is a perpendicular force.
The only force acting on the blue mass cannot increase its speed.
The speed of the blue mass remains as constant as any other mass subjected to a perpendicular force.
To claim that
collision the blue ball is moving at 5 units along the new line of travel,is an expression of your belief, it has no basis in science
Post by: Origin on 18/08/2023 12:16:40
is an expression of your belief, it has no basis in scienceNo it is a straight forward use of physic and math.
You stated that after the collision the blue ball was moving at 4 units along the x-axis and 3 units along the y-axis.
Based on this please answer this simple question: What is the speed of the blue ball along its direction of travel?
After you answer the first question could you also answer this question? If the red ball was initially moving at 20 units so the final speed of the blue ball 4 units along the x-axis and 20 unit along the y-axis what would the balls speed be along the direction of travel?
One final question. This does not have anything to do with a collision. A green ball is moving with a speed of 5 m/s along the x-axis and 5 m/s along the y-axis. What is the speed of the ball along its direction of travel?
Thanks
Post by: Origin on 18/08/2023 12:53:30
Perpendicular force.Nope. Your collision scenario is not an example of centripetal force.
Changes the velocity of a moving mass
By changing the direction of the mass.
It is also known as centripetal force.
The only force acting on the blue mass cannot increase its speed.This is just something that you made up. Please supply any sources that support your claim that a collision that occurs between 2 balls at a right angle will not increase the speed of one of the balls (except for the trivial example where the balls have the same mass and speed).
The speed of the blue mass remains as constant as any other mass subjected to a perpendicular force.
Post by: Momentus on 18/08/2023 16:16:13
What is the speed of the blue ball along its direction of travel?I assume that you have not read any of the posts where I state. The speed of the blue ball does not change.
Post by: Momentus on 18/08/2023 16:19:17
Please supply any sources that support your claimSir Issac Newton The principia.
Post by: Origin on 18/08/2023 17:08:48
the posts where I state. The speed of the blue ball does not changeI am afraid we are at an impasse here because you do not understand the basics of motion and basic math.
You believe that a point located at x=4 units and y=3 units is 4 units from the origin. This is just plain wrong and is something you should have learned in highschool. The worst part is you refuse to learn. Oh well...
Post by: Momentus on 18/08/2023 17:14:12
The blue mass is moving at a speed of 4 units in the direction AC as shown in the diagram.
A perpendicular force is applied to the mass by an interaction with a red mass, bringing the red mass to rest. The red mass has a speed of 3 units, bringing the mass to rest imparts a momentum of 3m to the blue ball.
This changes the momentum of the blue mass by 3m. Equal and opposite exchange of momentum, opposed force.
Momentum is a vector quantity of mass and velocity. When the mass is not changed any change in momentum is brought about by a change in velocity.
Velocity can be changed by Altering speed and by altering direction. Either separately or in combination.
To change the speed of a moving mass a force must be applied along the line of motion of the mass.
To change the direction of a moving mass, a force must be applied perpendicular to the mass.
Applying these rules to the blue mass will alter the direction on the mass so that it is moving at a speed of 3 units along the line of action of the force, that is perpendicular to its original direction of travel. This is an equal and opposite exchange of momentum with the red mass.
This is achieved by opposing forces, the force to accelerate the red mass to a halt is opposed by the force required to accelerate the blue mass into a new direction.
Note there is no force left over to act along the line of motion of the blue mass. It has all been used up. There is no momentum left over from the collision, it has all been accounted for.
As there is no force to act along the line of action the speed of the blue ball is not changed.
The blue mass is now moving at a speed of 3 units in the direction perpendicular to the original line of motion. Accounting for all of the momentum given up by the red mass, All of it.
It is also moving at a speed of 4 units in an as yet undetermined direction.
The direction that the blue mass is now moving can be determined by simple geometry. It is moving along the hypotenuse of a right-angled triangle at 4 units and along the perpendicular side of the triangle at 3 units. Just as drawn in the original diagram.
That is Dark Motion.
Post by: Bored chemist on 18/08/2023 17:27:43
But Newtonian physics doesn't seem to explain the observed behaviour of matter in space.
The only way it works is if you add "dark matter" etc.
So, your idea is either "Newtonian", in which case it doesn't remove the need for dark matter or it's something new, in which case you shouldn't say things like
That is Dark Motion.There's nothing "dark" about it.
Essentially, your ideas are wrong, or they are irrelevant.
Which i sit?
Post by: Momentus on 18/08/2023 19:26:13
your ideas are wrongWhich bit is wrong? I have worked an example from first principles.
Post by: paul cotter on 18/08/2023 20:26:40
Post by: Origin on 18/08/2023 23:54:24
It is also moving at a speed of 4 units in an as yet undetermined direction.I'm sorry that you can't work out this problem. But since you don't know how to do the math it doesn't make much sense for you to claim you can guess the answer.
If you do the math you will find that the speed of the blue ball is 5 units and at an angle that is 36.9 degrees from the x-axis.
Post by: Bored chemist on 19/08/2023 00:38:53
Which bit is wrong?Answering that is your job, not mine.
I just pointed out that your post is either wrong or irrelevant.
Post by: Momentus on 20/08/2023 12:16:15
I'm sorry that you can't work out this problem. But since you don't know how to do the math it doesn't make much sense for you to claim you can guess the answer.
The direction that the blue mass is now moving can be determined by simple geometry. It is moving along the hypotenuse of a right-angled triangle at 4 units and along the perpendicular side of the triangle at 3 units. Just as drawn in the original diagram.
Post by: Momentus on 20/08/2023 13:01:38
I copied the diagram he used to show what happens when a body is subjected to a perpendicular force.
In this drawing he represents the direction of the mass by a drawn line, and the speed of the mass by the length of the line. His drawing shows that the length of the line is not changed by the applied impulse.
In the drawing he repeats the action, changing the direction of the line, but not the length of the line.
He does this repeatedly with the same result, perpendicular force, change of direction, constant speed.
Form this he goes on to derive centripetal force and his theory of gravity.
My diagram shows exactly the same thing as Newton?s 350 year old drawing.
Perpendicular force changes the direction of a moving mass. It does not change the speed.
Post by: Origin on 20/08/2023 13:34:41
My diagram shows exactly the same thing as Newton?s 350 year old drawing.A collision is not an example of centripetal force.
Perpendicular force changes the direction of a moving mass. It does not change the speed
In Newtons model of orbital motion there is a continuous force that is perpendicular to the direction of an objects motion. In a perfectly circular orbit the objects speed would be constant, only the direction would change. That is not what we are talking about here. There is no continuous force, you are trying to apply centripetal force to a situation where it doesn't apply.
Post by: Bored chemist on 20/08/2023 14:15:49
The diagram shows a blue ball traveling at a velocity of A-C, which is struck by a red ball traveling at a velocity of B-C.What happens to the kinetic energy of the red ball?
The Blue ball is deflected with a resultant velocity C-D, the vector change is solely of direction, the red ball comes to rest its vector change is solely of magnitude.
Post by: Momentus on 20/08/2023 19:14:02
speed would b constant, only the direction would changeFinally some understanding of perpendicular force.
In the principia Newton uses impulses, to establish centripetal force, only moving on to continuous force at the end
Post by: Momentus on 20/08/2023 19:28:17
What happens to the kinetic energy of the red ball?I think that is an excellent observation. Do you recall the title of the thread?
Kinetic energy only seems to have a value within a particular frame of reference, as you point out.
There is a relationship between speed and mass (E=mc2) which must apply to the red ball, even though the change must be infinitesimally small. The asymmetrical nature of dark motion raises many such queries.
Post by: Bored chemist on 20/08/2023 20:07:10
I think that is an excellent observationIt wasn't an observation, it was a question.
And it's a question which you failed to answer.
Post by: Origin on 20/08/2023 20:28:45
Finally some understanding of perpendicular force.I think everyone here understands centripetal force and they also know that centripetal forces are different than a collision of 2 masses, which is something that you don't understand.
Post by: Origin on 20/08/2023 20:32:00
The asymmetrical nature of dark motion raises many such queries.I think you have clearly proven that your idea of dark motion is just your misunderstanding of basic Newtonian mechanics.
Post by: Momentus on 21/08/2023 10:28:09
I think everyone here understands centripetal force and they also know that centripetal forces are different than a collision of 2 masses, which is something that you don't understand.The collision of two masses provides a force, which arises from the deceleration of the red ball. Newton, in the passage from the Principia which I have quoted, uses an impulse to change the direction of a mass. He then uses calculus to extend the proven case of a single impulse into a continuous force.
He shows that a perpendicular impulse changes the direction of a mass and does not change the speed, just as the diagram I have posted.
It is of no consequence that in your opinion the popular vote supports your argument. Science depends upon facts not belief.
Post by: Bored chemist on 21/08/2023 10:35:39
Science depends upon facts not belief.The facts of dark matter and dark energy are established.
Your belief that they have anything to do with your diagram is irrelevant.
I'm curious.
What do you think the phrases "dark matter" and "dark energy" mean?
Post by: Momentus on 21/08/2023 12:27:30
Post by: Origin on 21/08/2023 12:35:19
He shows that a perpendicular impulse changes the direction of a mass and does not change the speed, just as the diagram I have posted.No, your chart clearly shows that the speed increases.
Before the collision the blue ball is moving at 4 units of speed along the x direction and 0 units in the y direction so the overall speed is 4 units.
After the collision the blue ball is moving 4 units in the x direction and 3 units in the y direction so the overall speed of the blue ball is 5 units.
You have shown in your diagram that the speed increases.
The only conclusion I can come up with is either you simply unable to understand basic math and basic Newtonian mechanics or you are a troll.
If it is simple ignorance, it is too bad you refuse to accept any help to clear up your understanding.
Post by: Momentus on 21/08/2023 13:33:39
No, your chart clearly shows that the speed increases.Newton's "chart" shows that the speed does not increase. My chart is the same as Newton's "chart".
Why do you refuse to acknowledge this.?
Post by: paul cotter on 21/08/2023 13:46:42
Post by: Bored chemist on 21/08/2023 13:48:10
My chart is the same as Newton's "chart".No, it's not.
The string holding a ball to a circular path does no work.
A ball colliding with something and stopping does do work.
Why do you refuse to acknowledge this.?
Because it's wrong.
Post by: Origin on 21/08/2023 14:09:13
Newton's "chart" shows that the speed does not increase.Newtonian mechanics says the speed increases.
My chart is the same as Newton's "chart".Your chart shows that the speed increases. It is right there in your math and you show that the speed is 5 units. The fact that you show the speed increases and then state that the speed doesn't increase is rather insane.
Why do you refuse to acknowledge this.?Because I'm not insane.
This is pointless! Normally I would do the math to show you that you are incorrect and the speed increases except you have already done that and proven that you are wrong.
Absolutely bizarre. :o
Post by: paul cotter on 21/08/2023 15:16:38
Post by: Momentus on 24/08/2023 11:36:46
n Newtons model of orbital motion there is a continuous force that is perpendicular to the direction of an objects motion. In a perfectly circular orbit the objects speed would be constant, only the direction would change. That is not what we are talking about here. There is no continuous force, you are trying to apply centripetal force to a situation where it doesn't apply.
Isaac NEWTON: Philosophiae Naturalis Principia Mathematica. 3rd Ed.
Book I Section II.
Translated and Annotated by Ian Bruce. Page 95
SECTION II. On the finding of centripetal forces.
PROPOSITION I. THEOREM I.
Truly, when the body comes to B, by a single but large impulse the centripetal force acts, and brings about that the body deflects from the line Bc and goes along in the line BC ; cC is acting parallel to BS itself, crossing BC in C; and with the second part of the time completed, the body (by the corollary to Law I.) may be found at C
Newton Centripetal.png (25.16 kB . 221x219 - viewed 31 times)
By a single but large impulse the centripetal force acts
Those are Newton?s words,
Newtons model of orbital motion there is a large but single force that is perpendicular to the direction of an objects motion. The objects speed would be constant, only the direction would change.
Post by: Momentus on 24/08/2023 11:46:31
You believe that a point located at x=4 units and y=3 units is 4 units from the originThat would be the point on the drawing marked X. So yes I can do simple vectors.
Post by: Origin on 24/08/2023 12:01:27
That would be the point on the drawing marked X. So yes I can do simple vectors.You can do simple vectors? Great, what is the magnitude of the vector that goes from the origin to your point 'x'?
Post by: Momentus on 24/08/2023 13:09:48
That means the blue ball is moving 4 units in the x direction and 3 units in the y direction which means the ball is moving at 5 units along a line that is 36.9 degrees from the CD line (x-axis).
A large impulse changes the momentum of the blue ball. The change in momentum is accomplished by a change in velocity. Velocity is a vector quantity of speed and direction.
A change in direction does not involve a change of speed. If you are coasting along on your bicycle at 4 mph and you turn, change direction, your speed remains at 4 mph.
There was a force interaction between your tyres and the road. That force did not change your speed. You need to pedal, apply a force along your line of motion to change your speed. So The bicycle was moving at 4 units in the x direction, and is now has a resultant speed of 4 mph, with vectors of 3 units in the y direction and 2.6 in the x direction.
The blue ball is moving at an unchanged speed of 4 units the vector sum of 3 units in the y direction and 2.6 units in the x direction
Which is shown by the original drawing.
Post by: Origin on 24/08/2023 13:34:29
The blue ball is moving at an unchanged speed of 4 units the vector sum of 3 units in the y direction and 2.6 units in the x directionYou are arguing in bad faith. Or to put it more simply you are lying.
Which is shown by the original drawing.
You originally said that the blue ball was moving at 4 units in the x-direction after the collision:
That change is shown in the diagram as the red mass coming to rest, no residual momentum, the blue mass moves on the line of CD an unchanged speed of 4 units and also along the line of BC at speed of 3 units.
Now you dishonestly say that you have always said the ball is moving at 2.6 units in the x-direction.
It is obvious why you made up this lie, it because your original numbers result in the ball moving at speed of 5 units after the collision, which is not what you 'want' the answer to be.
Now that you have decided to make up the speed of 2.6 units in the x-direction after the collision, could you identify the force that caused the deceleration of the blue ball from 4 units to 2.6 units?
Edit: Just to let you know, if you want to stick with the new made up number of 2.6 units then your example violates the conservation of momentum! You seem to be painting yourself into a corner...
Post by: Momentus on 24/08/2023 15:53:08
You originally said that the blue ball was moving at 4 units in the x-direction after the collision:No you have made that up. Tell me which post I said that in. Use the quote function.
it because your original numbers result in the ball moving at speed of 5 units after the collisionThat is what you have said, not me. I have never said that the blue ball moves at anything other than 4 units.
I guess you could not follow the bicycle example, or relate it To my quotes from the Principia
.
Now you dishonestly say that you have always said the ball is moving at 2.6 units in the x-direction.This is my first mention of 2.6 units. It is the first time that I have calculated it. It arose from the bicycle analogy.
It is obvious why you made up this lie, it because your original numbers result in the ball moving at speed of 5 units after the collision, which is not what you 'want' the answer to be.
I have quoted examples from the Principia which show that Newton established that the mass does not speed up. What supports your fantasy that a perpendicular force increases the speed of a mass?
Post by: paul cotter on 24/08/2023 16:05:13
Post by: Momentus on 24/08/2023 16:46:14
Halc's example simply refutes your spurious claim.Which post refers?
Post by: Momentus on 24/08/2023 16:54:54
If one applies a force at 90 degrees to an object in motion the velocity component in the original direction will not change but acceleration will undoubtedly occur in the direction of the applied force.Yes and that acceleration will be due to a change of velocity by changing direction.
It does not speed up from 4 units to 5 units
Post by: Bored chemist on 24/08/2023 17:13:21
Do you plan to tell us where the kinetic energy of the red ball went?I think that is an excellent observationIt wasn't an observation, it was a question.
And it's a question which you failed to answer.
Or are you saying the laws of physics don't apply to you?
Post by: paul cotter on 24/08/2023 17:30:20
Post by: Origin on 24/08/2023 23:36:27
No you have made that up. Tell me which post I said that in. Use the quote function.
You are arguing in bad faith. Or to put it more simply you are lying.I was wrong on this. I have been suffering under the impression that you had said the the blue ball continued moving in the x-direction at 4 units. But that is not what you wrote. Sorry for my misunderstanding, my bad.
I guess I assumed you said that since that is what would actually happen.
The overall speed of the blue ball after the collision is not 4 units, that of course would violate the conservation of momentum. The x component of the blue balls velocity is not 2.6 units. Since there was no force from the collision that was in the x direction the speed in the x direction remains unchanged at 4 units.
Post by: paul cotter on 25/08/2023 10:53:54
Post by: Origin on 25/08/2023 12:27:36
Still we have the problem where the OP will not accept that a force at right angles can influence the speed of the mass.Agreed.
The only part of the problem that the OP got correct is that the blue balls speed in the y direction goes from 0 m/s before the collision to 3 m/s in the negative y direction after the collision.
It is rather humorous that the OP says a force that is perpendicular to a moving ball cannot change the speed of the ball and then turns around and says that the blue ball does increase in speed from 0 to 3 m/s in the y direction.
Since he says the blue balls speed increases to 3 m/s in the y direction (which is correct) he has to say the blue balls speed in the x direction decreases from 4 m/s to 2.6 m/s (which is wrong) so that his fantasy that the overall speed of the blue ball doesn't change.
The reality is that the blue balls speed in the x direction will not change since the impulse from the collision is only in the y direction. So after the collision the blue ball has an x component of velocity that is 4 m/s and a y component of velocity that is 3 m/s. The overall velocity is 5 m/s after the collision. That is pure Newtonian mechanics.
Post by: Momentus on 25/08/2023 15:26:18
By your assertions, the ball will attain a new velocity of 0.1 m/sec mostly west and will only make it past the edge of the track because it's falling off the tee and not go 200 meters.The angle at which the ball moves after the collision is proportional to the impulse.
As the angle approaches 90 degrees the force approaches infinity, an irresistible force against an immovable object.
My guess is that would be as near to 90 degrees as makes no difference. The club is not free to stop at the point of impact, it is being "driven through". The golf ball is deformed by the impact and rebounds off the club head, which is still moving. The experiment is a thought experiment. The analysis would be complex.
Post by: paul cotter on 25/08/2023 16:32:31
Post by: Momentus on 25/08/2023 16:51:35
Still we have the problem where the OP will not accept that a force at right angles can influence the speed of the mass.
Speed is distance travelled along line of motion over time, i e m/s.
Newton is quite clear on this point. Force along the line of action changes speed. Perpendicular force changes direction. He furthermore says that an oblique force can be resolved into linear and perpendicular forces which will change speed and direction respectively.
The OP suggests that you read the Principia before making a complete fool of yourself.
blue balls speed in the y direction goes from 0 m/s before the collision to 3 m/s i
It is rather humorous that the OP says a force that is perpendicular to a moving ball cannot change the speed of the ball and then turns around and says that the blue ball does increase in speed from 0 to 3 m/s in the y direction.
No The OP did not say that.
The diagram shows a blue ball traveling at a velocity of A-C, which is struck by a red ball traveling at a velocity of B-C.
The Blue ball is deflected with a resultant velocity C-D, the vector change is solely of direction, the red ball comes to rest its vector change is solely of magnitude.
Speed is distance travelled along line of motion over time, i e m/s. The speed of the blue ball along its direction of travel at all times is 4 units.
The motion of 3 units is a vector on the x axis of the speed of the blue ball after its direction has been changed by the perpendicular impulse. How is that humorous?
Post by: Origin on 25/08/2023 17:52:04
The OP suggests that you read the Principia before making a complete fool of yourself.Don't concern yourself, I have taken university physics and I know how to do a collision problem.
Speed is distance travelled along line of motion over time, i e m/s. The speed of the blue ball along its direction of travel at all times is 4 units.This is wrong based on Newtonian mechanics and experimentation.
The motion of 3 units is a vector on the x axis of the speed of the blue ball after its direction has been changed by the perpendicular impulse. How is that humorous?It is humorous/sad that you think a force in the y direction can somehow change the speed of something moving in the x direction.
You are completely confused about this whole scenario. Don't you wonder why everyone here is telling you that you are wrong?
Post by: Origin on 25/08/2023 19:46:10
It is rather humorous that the OP says a force that is perpendicular to a moving ball cannot change the speed of the ball and then turns around and says that the blue ball does increase in speed from 0 to 3 m/s in the y direction
No The OP did not say that.You most certainly did:
the blue mass moves on the line of CD an unchanged speed of 4 units and also along the line of BC at speed of 3 units.The line BC is the y-axis.
I don't know why you want to deny this since it is the only part of the problem that you got right!
In your example you state that the red ball moving at 3 m/s in the -y direction hits the blue ball, the red ball stops and the blue ball accelerates to 3 m/s in the -y direction. This means that 100% of the KE was transferred from the red ball to the blue ball and the transfer occurred in the y-direction. We know this because the velocity in the y direction is the same before and after the collision.
You claim that the speed of the ball in the x direction slowed down from its original speed of 4 m/s. There is no force that you have identified that would cause that to happen.
Your big misconception is that you have got it in your head that a perpendicular collision of a moving object cannot change the speed of that object, which is wrong. You seem to have gotten that impression because of how a centripetal force works. I will say the obvious once more; a collision and centripetal forces are 2 different things.
Post by: Momentus on 28/08/2023 14:34:51
A point of view from the ?other side.
I would liked to have discussed a simple force/momentum reaction which appears to have profound implications regarding dark matter and dark energy.
I am an amateur interested in science, with an engineering background. My expectation was that those who chose to respond to my post would have knowledge greater or at least similar to mine.
In my description I assumed that perpendicular force did not change speed, only direction. I thought that was axiomatic. It is the nature of centripetal force after all.
The moderator does not agree. Has the right, forum rules, to move the post and exercised that right.
Now my post is in there with the loonies, trolls and posters who will not listen to good advice.
I tried a second post
If a force is applied perpendicular to an object's velocity, it will alter the direction of motion without changing the speed.
I think that this applies to a blue ball rolling down a snooker table and struck by a red ball rolling across the table
Also, the red ball stops at the point of impact.
I cannot see how it can behave in any other way, but seek confirmation.
Now that is a polite scientific question. Moved to the weird science forum.
How do you explain something to a naked science god who dismisses Newton's proof of centripetal force as irrelevant?
I did not post with the expectation that basic laws of motion would be ignored, but to discuss the effects of applying the laws, as written, to a specific simple example.
Nobody who actually has a valid new theory is going to publish it in a forum. New ideas are not going to come out of here.
I think that sums up the Naked Science forum view of New Theories, and the moderators will do their best to ensure that outcome.
Post by: Origin on 28/08/2023 15:02:57
In my description I assumed that perpendicular force did not change speed, only direction. I thought that was axiomatic.This is exactly why your post should be under 'New Theories'.
In your example the conservation of momentum is violated. A scenario involving a violation of the conservation of momentum would indeed be a 'new theory'.
In you example a body can decelerate from 4 m/s to 2.6 m/s with no force applied. This is a violation of Newtons first law which indeed is a new theory.
How do you explain something to a naked science god who dismisses Newton's proof of centripetal force as irrelevant?Your example was about an elastic collision and not about a centripetal force.
I do sort of agree that your posts should not be under the heading of 'New Theories', they should be under the heading of 'cesspool' or 'Garbage Can' because your 'theory' does not agree with experimentation. In other words your hypothesis has been falsified right off the bat by hundreds of years of experimentation.
Post by: Origin on 28/08/2023 15:23:43
I am an amateur interested in scienceAs an amateur you should listen to people who have more knowledge than you. You have been conversing with actual physicists (not me I'm a retired engineer) who have tried to point out your errors, You have ignored all attempts to help you, this attitude is not conducive to learning more about the subject you claim to be interested in.
I realize that you think you have discovered something new which very exciting for you but the truth is you are not understanding the underlying physics. You have 2 choices, you can listen to the advice from others and explore their suggestions or you can continue to believe your 'theory' that does not match reality.
In the long run it makes no difference which route you choose, but don't expect anyone to agree with your erroneous ideas.
Post by: Momentus on 28/08/2023 15:54:05
Your example was about an elastic collision and not about a centripetal force.Consider if you can, if you are able to, a case where a force of which you approve, which meets your unstated yet specific needs is exerted on a moving body, perpendicular to the motion of said body, just like Sir Isacc Newton proposes in the passage I have already quoted for you.
Ignore all my ignorance cess pit garbage and nonsense, if you can, and answer the very simple question.
Perpendicular force does not change the magnitude component of velocity. it changes the direction and only the direction.
A simple answer of yes or no, with some outside reference will be appreciated. Teach me O guru of science
Post by: Momentus on 28/08/2023 16:04:19
Your big misconception is that you have got it in your head that a perpendicular collision of a moving object cannot change the speed of that object, which is wrong. You seem to have gotten that impression because of how a centripetal force works. I will say the obvious once more; a collision and centripetal forces are 2 different things.Is there really no one reading this with the courage to call this Naked Science King out on this nonsense
Post by: Bored chemist on 28/08/2023 17:13:49
Perpendicular force does not change the magnitude component of velocity. it changes the direction and only the direction.Well, here's my take on it:
That's still more or less guaranteed to be wrong..
If a force acts on something it changes the momentum of the thing.
In one odd sort of case it may change just the direction.
That case is when you have something like a mass being swung round on a string.
But that's not the case you drew in your OP.
The reason that the " mass on a string" case is different is what happens if you consider the moments (periods of time not the thing related to torque) just before and after the time when it exerts a perpendicular force. Here's a bad picture
BAD PICTURE.png (8.51 kB . 591x425 - viewed 362 times)It shows the circular path of a mass traveling clockwise (as indicated by the arrow) at three instants in time T1, T2, T3. It also shows the force (acting towards the centre) at those times F1 F2, F3.
As I said, it's a bad picture, please pretend that at T2 the line from the centre to the body is vertical.
At T1 there's a component of the force F1 acting horizontally left to right.
And at T3 there's a component of the force F3 acting horizontally right to left.
As you make the time intervals between T1 and T3 small enough those two horizontal forces tend to cancel out.
And, for zero time they exactly cancel. The only force acting is in towards the centre of the circle. But only for zero time.
You can do that if you have a bit of string or something.
But you can't do it with colliding bodies because there's no opportunity of the sideways forces to be averaged out to zero
Which is why I asked this
What is the difference between something that does not happen, and something that can only happen if you do something impossible?
It's a pity you didn't think to answer that at the time.
Because it's the distinction between the case of an object moving in a circle- like Newton described- and the case you drew in the OP.
That's why he's right and you aren't.
And the whole of this offshoot of the tread should be moved to the other thread, rather than this one about how much clutter there is in "New Theories"
Post by: paul cotter on 28/08/2023 17:53:12
Post by: Bored chemist on 28/08/2023 17:55:28
Is there really no one reading this with the courage to call this Naked Science King out on this nonsenseI have plenty of courage.
But... he's right.
Post by: paul cotter on 28/08/2023 18:09:53
Post by: Origin on 29/08/2023 01:56:26
Is there really no one reading this with the courage to call this Naked Science King out on this nonsense
Let's do a quick check to see who is talking nonsense.
First and foremost we know that in an elastic collision the KEi = KEf.
The KE before the collision.
Assume the velocities are m/s.
Assume the masses are 1 kg (to make it easy and clear)
Blue ball: 1/2m*v^2 = 1/2(1 kg)*(4 m/s)^2 = 8 J
Red ball: 1/2m*v^2 = 1/2(1 kg)*(3 m/s)^2 = 4.5 J
Total KE = 8 J + 4.5 J = 12.5 J
KE after the collision.
Blue ball: I say the x component of the velocity is 4 m/s and the y component of the velocity is 3 m/s, this gives an overall velocity of 5 m/s.
You say the x component of the velocity is 2.6 m/s and the y component of velocity is 3 m/s, this gives an overall velocity of 4 m/s. (A 2.6 m/s velocity in the x direction does not give an exact overall velocity of 4 m/s, but it is close enough).
We both agree that the red ball is stationary.
So the KE after the collision should still be 12.5 J.
Red ball: 1/2m*v^2 = 1/2(1kg)*(0m/s)^2 = 0 J.
Your numbers, Blue ball: 1/2m*v^2 = 1/2(1kg)*(4m/s)^2 = 8 J.
Total KE: 0 J +8 J = 8J
KEi = 12.5 J
KEf = 8 J
For your numbers KEi ≠ KEf.
Your answer cannot be correct.
Red ball: 1/2m*v^2 = 1/2(1kg)*(0m/s)^2 = 0 J.
My numbers, Blue ball: 1/2m*v^2 = 1/2(1kg)*(5m/s)^2 = 12.5 J.
Total KE: 0 J + 12.5 J = 12.5 J
KEi = 12.5 J
KEf = 12.5 J
For my numbers KEi = KEf.
The final speed must be 5 m/s not 4 m/s.
Post by: Momentus on 31/08/2023 15:32:07
Well, here's my take on it:Newton did it 350 years ago. I quote him in my post. Read what he says and then review your post.
Post by: Momentus on 31/08/2023 15:37:07
Let's do a quick check to see who is talking nonsense.This is a straw man. A very good straw man, but in no way applicable to centripetal force.
First and foremost we know that in an elastic collision the KEi = KEf.
With centripetal force, as shown by Newton, there is no change in magnitude, therefore there can be no energy exchange.
Centripetal force does not change Speed.
Post by: paul cotter on 31/08/2023 16:09:47
Post by: alancalverd on 31/08/2023 17:10:56
A bug, mass 0.1 gram, is flying from west to east at 1 m/s (heading and track090) when he is hit by a 10 gram bullet travelling south to north (heading and track000) at 1000 m/s.
Using simple vector addition you can calculate the resulting velocity of the bullet with the squished bug. It's pretty close to 999.99 m/s track 000.001, so yes, the bug is still heading 090 at 1 m/s but is unlikely to reach his original destination.
Post by: Momentus on 31/08/2023 17:13:01
Centripetal force is associated with circular motion.In the passage from Newton's Principia,
by a single but large impulse the centripetal force acts, and brings about that the body deflects from the line Bc and goes along in the line BC
The diagram shows a blue ball traveling at a velocity of A-C, which is struck by a red ball traveling at a velocity of B-C.which I have quoted for you he shows how to derive centripetal force. If you were to read it you would see that he uses an impulse to change the direction of a moving mass. This forms a polygon, as per the example.
The Blue ball is deflected with a resultant velocity C-D,
Newton Centripetal 3.png
You refer to collision as if it were some special force, with strange properties. A collision gives an impulsive force.
You refer to Halc?s ?experiment? as conclusive proof. He has not performed any experiments.
If you exert a very large perpendicular force to a slow-moving mass the momentum vector will be turned through 90 degrees by the impact, which will use only a fraction of the momentum of the large perpendicular force. The remainder of the momentum will then act in the direction of travel and will no longer be a perpendicular force.
When Halc does perform the experiment I suggest he exerts the force in increments, starting with a small force and building up to his golf club swinging maximum.
Post by: Bored chemist on 31/08/2023 17:21:23
Unlike you, Newton understood that motion in a curve is not the same as motion in a straight line.Well, here's my take on it:Newton did it 350 years ago. I quote him in my post. Read what he says and then review your post.
So it's not me who needs to review my position.
Post by: Origin on 31/08/2023 18:46:39
This is a straw man.I looked but I can't find this strawman you are talking about. The example you gave was about an elastic collision in which the KE is the same before the collision as after the collision. I calculated the KE before and after the collision based on your numbers and my numbers, so where is the strawman?
Are you seriously trying to say in your example that the conservation of energy does not hold?? Does that seem even remotely possible?
I suppose calling a collision a centripetal force is a strawman, but that is your strawman not mine.
Post by: paul cotter on 31/08/2023 18:53:05
Post by: Origin on 31/08/2023 19:00:27
In the passage from Newton's Principia,You apparently fail to understand that in a centripetal force, the force is continuously orthogonal to the movement of the body. A momentary impulse is not what Newton is talking about This misunderstanding is resulting in you tossing out most of Newtonian mechanics to try and protect this wrong notion.
If you are really interested in physics, you could take an introductory course in physics at a local community college (probably for free) and learn what is really going on.
Again I would like you to ponder why people who have actually been educated in physics are all telling you that you are wrong. Do you think that no one noticed this error for 400 years except you? Does that make sense to you?
Post by: Origin on 31/08/2023 21:08:54
You refer to collision as if it were some special force, with strange properties.You aren't say the conservation of energy is a strange property, are you?
The only strange property I have seen in your example, is the one where you think the speed of the blue ball in the x direction decelerates for no reason. This of course leads to the even stranger property which is the violation of the conservation of energy, which apparently is of no concern to you.
Post by: Halc on 31/08/2023 23:31:34
You refer to Halc?s ?experiment? as conclusive proof. He has not performed any experiments.Proof? Hardly. But I did do it. Looked a lot like your setup, but the impacts were more random.
It was done in the dark with silver balls and a strobe light reflecting onto photo-sensitive paper, leaving a series of black dots each time the strobe went off.
Afterwards, speed and direction were measured by connecting the dots and noting their separation. In each case, the momentum and energy was conserved (within the precision of the experiment, which wasn't very high since it wasn't done in a vacuum and in absence of friction.
Your asserted interactions do not conserve energy. That would mean that warm water would cool to below freezing in under a second given how much energy is lost in your single example collision. Molecules collide often in water, so if on average a third of the energy is lost with each collision (as it was in your example), then the water would cool in far less than a second.
if you can, and answer the very simple question.This is true, and Newton would agree. I agree that some of the posters do not agree with this.
Perpendicular force does not change the magnitude component of velocity. it changes the direction and only the direction.
Quote
Teach me O guru of scienceOK.
Your force is not being applied perpendicular to the motion of the body in question. This has been repeatedly pointed out, and repeatedly ignored. So the conclusion that the speed doesn't change is false since it is based on a false assumption.
The finite force is applied over a nonzero period of time, albeit a short one. Else there would be no momentum exchange since momentum transfer is force*time.
Sure, the force is initially tangential to the motion, but as the path curves and the force peaks, the curvature brings the trajectory halfway between the inbound trajectory and the outbound one, about an average angle of 81o or so. Hence the force accelerates the blue ball since it is always (at any nonzero duration of time) applied partially in the direction of motion.
None of this is true in centripetal acceleration where the force is perpendicular to the motion (in at least the frame of the center of rotation) the entire time. In that frame (and not in any other) does the 'orbiting' object not change speed.
The alternative (that Momentus seems to push) is that the force is applied only to a horizontal-trajectory blue ball, and only once this force concludes, does the ball begin to accelerate downward. Both the force not causing any initial acceleration, and the later acceleration without a force being applied, are total violations of the laws of motion.
Post by: Origin on 01/09/2023 02:30:17
Your force is not being applied perpendicular to the motion of the body in question.Could you expound on this point please. I am not sure I understand what you are saying here.
Post by: paul cotter on 01/09/2023 09:16:08
Post by: Halc on 01/09/2023 16:36:38
The bullet in the breech is obviously travelling at 100km/h and I now pull the trigger and the bullet flies off at 700m/s. The bullet continues it's travel in the direction of the train at 100km/h but now has a speed of 2520km/h.Exactly, so the force on the bullet cannot always have been perpendicular to its motion.
The force is applied over say 100 usec (a 10th of a msec) which would yield ~700 m/sec over the length of a handgun barrel. We'll assume for simplicity that the force is constant for those 100 usec and zero before and after.
At time 0 the force becomes nonzero, and applied perpendicular to the bullet's initial 28 m/sec motion. After 0.1 usec (a thousanth of the total acceleration time), the bullet has accelerated 0.7 m/sec to the side. Total speed is 28.009 m/sec, which is pretty much the same speed as before because the force is mostly being applied perpendicular to the motion.
But now the bullet is already moving at 0.7 m/sec to the side and any continued force in that direction is now partially behind it, not perpendicular. The speed relative to the tracks begins to climb significantly.
After 10 usec (10th of the time under acceleration, 1/100th of the distance down the barrel, the bullet is now moving at 70 m/sec left and 28 m/sec forward which is 75.4 m/sec total, and now the trajectory is already mostly to the side, so about 0.9 of the force (sin(70 deg))being applied to the bullet contributes to increasing its speed. So the vast majority of the acceleration is pretty much directly in line with the motion of the bullet, not perpendicular with it. Only at first (a nanosecond or so) is the force perpendicular.
Since the direction of the bullet motion changes and the force direction doesn't, the force does not remain perpendicular.
With orbits, as the trajectory changes direction, the force does in lockstep, so it is perpendicular at all times.
It's all the same with the balls, with about 100 usec of acceleration time, perpendicular only at first and not the rest of the time.
Post by: paul cotter on 01/09/2023 16:51:51
Post by: Momentus on 02/09/2023 15:44:33
by a single but large impulse the centripetal force acts,
This is a quote from @Origin
A momentary impulse is not what Newton is talking about
i
Perpendicular force does not change the magnitude component of velocity. it changes the direction and only the direction.
This is true, and Newton would agree. I agree that some of the posters do not agree with this.
Your force is not being applied perpendicular to the motion of the body in question. This has been repeatedly pointed out, and repeatedly ignored. So the conclusion that the speed doesn't change is false since it is based on a false assumption.
Isaac NEWTON: Philosophiae Naturalis Principia Mathematica. 3rd Ed.
Book I Section II.
Translated and Annotated by Ian Bruce. Page 95
SECTION II. On the finding of centripetal forces.
PROPOSITION I. THEOREM I.
Truly, when the body comes to B, by a single but large impulse the centripetal force acts, and brings about that the body deflects from the line Bc and goes along in the line BC
How is that not clear to you? The speed does not change when Newton says he applies an impulse perpendicular to the motion. Why should the speed change when, in my diagram, I apply an impulse perpendicular to the force?
Is your argument that a perpendicular force cannot be produced, that there is no way to reproduce Newton?s experiment? Or is is just my experiment?
Working from first principles Newton says that a perpendicular impulse, which incidentally he is happy to define as a centripetal force, Alters velocity by changing direction and not changing speed.
I am merely echoing what he said.
Post by: paul cotter on 02/09/2023 16:55:19
Post by: Momentus on 02/09/2023 17:21:31
You are echoing your own errors in your own echo chamber, impervious to reason and correction.Which part of my echoing Newton is in need of correction?
Post by: Origin on 02/09/2023 18:02:24
I am merely echoing what he said.Newton did not say a collision is a centripetal force.
Post by: Origin on 02/09/2023 18:09:46
Which part of my echoing Newton is in need of correction?The part where you say the x component of the blue balls velocity drops from 4 m/s to 2.6 m/s without a force causing it. Newton says that's impossible.
The other glaring error in your example is that it violates the conservation of energy.
These 2 errors shows beyond a shadow of a doubt that your analysis is wrong.
Post by: Bored chemist on 02/09/2023 18:10:15
Which part of my echoing Newton is in need of correction?Your insistence that movement in a straight line is the same as movement in a circle.
You say that.
Newton did not say that.
So, you are not, in fact, echoing Newton.
Post by: Origin on 02/09/2023 18:30:29
Likewise I would like to see your explanation of why the conversation of energy doesn't apply to your example.
Hopefully you will stop dodging these questions.
Post by: Momentus on 03/09/2023 14:59:22
Newton did not say a collision is a centripetal force.No said the same as I keep on saying. A perpendicular force. In my drawing I apply a perpendicular force. In his drawing he applies a perpendicular force. You are using collision as a debating point, it is irrelevant. Newton applied an impulse to a mass moving in a straight line. I apply the same impulse to a mass moving in a straight line
Newton says that's impossible.Do you have a source or did you just put words in Newton?s mouth?
Your insistence that movement in a straight line is the same as movement in a circle.Yes of course I did. Over and over and over. Quote me.
I would really like to see your explanation for why the x component of the blue balls velocity decreased.I have posted that the motion along the x axis is the vector of the blue ball moving at the same speed, in a new direction. Just as Newton shows in his drawing.
Likewise I would like to see your explanation of why the conversation of energy doesn't apply to your example.Back to your straw man. Newton?s drawing shows what happens. Start there. Prove Newton wrong.
How is that not clear to you? The speed does not change when Newton says he applies an impulse perpendicular to the motion. Why should the speed change when, in my diagram, I apply an impulse perpendicular to the force?
Is your argument that a perpendicular force cannot be produced, that there is no way to reproduce Newton?s experiment? Or is is just my experiment?
Working from first principles Newton says that a perpendicular impulse, which incidentally he is happy to define as a centripetal force, Alters velocity by changing direction and not changing speed.
I am merely echoing what he said.
I can see that trying to illustrate Dark Motion with a snooker ball example has caused confusion. My apologies. Look at Newtons example instead.
Post by: Origin on 03/09/2023 17:22:41
I have posted that the motion along the x axis is the vector of the blue ball moving at the same speed, in a new direction.That means the x component of the speed has changed from 4 m/s to ~2.6 m/s without any force in the x direction. That is not possible according to Newtons first law.
Your example shows the red balls impulse causes the blue ball to move in the Y direction. 100% of the energy / momentum of the red ball was transferred to the blue ball in the Y direction. This is obvious since the masses of the balls are the same and before the collision the velocity of the red ball was 3 m/s in the y direction and the blue balls velocity was 0 m/s in the y direction and after the collision the blue balls velocity was 3 m/s in the y direction and the red balls velocity was 0 m/s in the y direction. So where is the force that slows the x component of the blue balls velocity coming from? It can't be coming from the red ball since 100% of the red balls energy was transferred to the blue ball.
Arm waving is not the answer I am looking for. What is the physical reason the ball slowed down? Where is the force that causes the blue ball to slow down in the x direction, or are you claiming there is no need for a force to slow the ball?
Back to your straw man.Your problem is an elastic collision between 2 balls and my calculations are showing an elastic collision between the 2 balls. That is not a strawman. So you are either lying, you don't know what a strawman is, or are so woefully ignorant of physics that you can't follow my calculations. Which is it?
I think it is time to close this thread. The OP refuses to listen any help provided and refuses to answer questions in good faith. He just keep repeating his misconceptions.
Post by: Origin on 03/09/2023 17:56:06
I can see that trying to illustrate Dark Motion with a snooker ball example has caused confusion. My apologies. Look at Newtons example instead.Why would we look at Newtonian mechanics? You said your "dark motion" is something that Newton missed, so Newtons laws and mechanics will be of little help. That is unless "dark motion" does use Newtonian mechanics, in which case why not call dark motion - just motion?
Post by: paul cotter on 03/09/2023 18:25:35
Post by: Momentus on 04/09/2023 17:46:20
Why would we look at Newtonian mechanics? You said your "dark motion" is something that Newton missed, so Newtons laws and mechanics will be of little help.
Are you being deliberately dense?
Philosophiae Naturalis Principia Mathematica.
SECTION II. On the finding of centripetal forces.
Newton?s first step is to show a simple action of force on a moving mass.
A trivial thing, he gives few words to the action. Simple and straightforward.
The action he describes is not reversible.
All the clever postings about rifles and gnats, revolvers and trains, Golf clubs and toys, kinetics and collisions, do not have any effect on Newton?s simple action, which he uses as a prelude to his complex centripetal force.
The action that Newton describes in his Finding of centripetal forces is not reversable. It is not symetrical.
Those are the facts.
My contribution is to identify this action and give it a name.
Dark Motion.
So go ahead and close the thread. I am tired of talking to obdurate assho
Brian Morris.
Post by: paul cotter on 04/09/2023 18:23:31
Post by: Origin on 04/09/2023 19:51:16
Those are the facts.The facts are that the collision problem as you describe it violates the conservation of momentum, the conservation of energy and Newtons first law of motion. In other words your description must be wrong. So that means you must be misunderstanding Philosophiae Naturalis Principia Mathematica. I'm not surprised since it is very hard to follow the language in the paper as it is 350 years old. Maybe you could look at a more recent text book on physics.
Post by: Origin on 04/09/2023 20:04:27
This is a discovery I made many years ago. I think you will find it a challenge to your beliefs. It is not a theory, it does not violate Newton's basic axioms too much and of course you can replicate the experiment very easily.
First you say that you have made a discovery that violates Newtonian mechanics (a little).
The action that Newton describes in his Finding of centripetal forces is not reversable. It is not symetrical.
My contribution is to identify this action and give it a name.
Dark Motion.
Now you say you have discovered nothing, you are just giving a name to part of Newtons explanation of centripetal force.
Which is it?
Post by: paul cotter on 04/09/2023 20:13:57
Post by: Halc on 04/09/2023 22:42:21
Nasty remarks like that only serve to demean he who delivers them.Momentus has earned a 10 day vacation for that remark, before which this topic will be closed, so no more posts here from him.
There will be a more careful watch on posts in other topics.
He is not open to anything that challenges his great discovery, as he sees it.Totally agree that logic, mathematics, and reason fall on deaf ears with this guy. He is here for the conflict, not to learn anything.
I suspect the ban will be permanent before too long.
Thanks to both of you for your efforts, which are noticed by the non-participating reader if not the OP.