# The Naked Scientists Forum

### Author Topic: Unstoppable object (moving), Unmoveable object (Still)  (Read 8885 times)

#### Seany

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##### Unstoppable object (moving), Unmoveable object (Still)
« on: 06/05/2007 22:52:54 »
Ok. Paul has given me a task, to ask one science-related question each day, for one week. So I am trying as hard as I can.

OK, there is an "unstoppable" object which is moving towards an "unmoveable" object. Assuming that the moving object is really unstoppable and the still object is really unmoveable, then what would happen to the moving object?

I think that the moving object would bounce off the unmoveable object at the same speed it travelled towards it. Is this right?

Would the unstoppable object lose energy, or keep the same amount of energy in which it used to travel towards it? Because if the object is unstoppable, then surely it cannot lose any energy at all?

#### JimBob

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #1 on: 06/05/2007 23:00:48 »
OK, Let's suspend Newton's Laws. Now assume Einstein was correct. The biggest nuclear explosion you have or will ever experience. It is the principal way both a fission and a fusion bomb works. The energy would be converted into another type of energy.

#### Seany

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #2 on: 06/05/2007 23:02:07 »
That being..?

#### JimBob

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #3 on: 06/05/2007 23:14:39 »
OK, I may need to be corrected on this but I think that the energy is from both mass and kinetic energy to heat.

I know the first atom bomb was made by having plutonium(?) hemispheres blasted by conventional explosives towards each other. The hemispheres are machined to very exacting tolerances so that they fit together very precisely. When the conversion to heat occurs, the air ruching back into the void created by the fission process causes the blast, just as when lightening makes thunder, but on a much, much large scale.

Now, can you figure out how I tricked you into accepting this answer?

#### Batroost

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #4 on: 06/05/2007 23:21:09 »
I think it's simpler than that:

Quote
OK, there is an "unstoppable" object which is moving towards an "unmoveable" object.

The existence of one negates the possibility of the existence of the other. In other words, whatever science you suspend in imagining the one, must automatically prevent the other from coming into being. Like many classic pardoxes this question turns out to be linguistic rather than physical...

Batroost (the cynic).

#### Seany

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #5 on: 06/05/2007 23:21:23 »
OK, I may need to be corrected on this but I think that the energy is from both mass and kinetic energy to heat.

I know the first atom bomb was made by having plutonium(?) hemispheres blasted by conventional explosives towards each other. The hemispheres are machined to very exacting tolerances so that they fit together very precisely. When the conversion to heat occurs, the air ruching back into the void created by the fission process causes the blast, just as when lightening makes thunder, but on a much, much large scale.

Now, can you figure out how I tricked you into accepting this answer?

Erm.. If it loses energy by transferring the kinetic energy, to heat energy, doesn't that mean by gradually hitting into more unstoppable object, the unmoveable object is going to slow down and eventually stop?

#### Seany

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #6 on: 06/05/2007 23:22:52 »
I think it's simpler than that:

Quote
OK, there is an "unstoppable" object which is moving towards an "unmoveable" object.

The existence of one negates the possibility of the existence of the other. In other words, whatever science you suspend in imagining the one, must automatically prevent the other from coming into being. Like many classic pardoxes this question turns out to be linguistic rather than physical...

Batroost (the cynic).

Hmm.. So you're saying that it is like the story where there are two sellers.

One of them is a shield seller, who says that no sword can ever pierce the shield.

The other seller is a sword seller, who says that this sword can pierce any shield.

#### JimBob

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #7 on: 06/05/2007 23:23:52 »
Nope. Try again. There is a basic logic flaw in the first post.

#### JimBob

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #8 on: 06/05/2007 23:25:35 »
OOPS, Batroost may have given you a head-start while I was typing.

#### Seany

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #9 on: 06/05/2007 23:26:18 »
Gwrr, I don't want some kind of quiz here!

#### JimBob

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #10 on: 06/05/2007 23:28:06 »
I am having a little fun with you (sorry  ) but if you do become a scientist, you will need to know basic logic. The flaw to my answer is this. In a universe where Newton's laws do not apply would Einstein's work be valid?

#### Seany

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #11 on: 06/05/2007 23:28:39 »
Newton's law and Einstein's law being..? They made a couple....

#### Batroost

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #12 on: 06/05/2007 23:33:13 »
Quote
The hemispheres are machined to very exacting tolerances so that they fit together very precisely. When the conversion to heat occurs, the air ruching back into the void created by the fission process causes the blast,

Yes the Trinity explosion, like the bomb dropped on Nagasaki, was a plutonium bomb. Hiroshima was Uranium-235. Actually only about 4% of the Plutonium was fissioned in in the explosion. The other 96% or so, along with the rest of the bomb was exploded outwards before more complete fissioning could occur. The primary blast is not caused by air rusing in, but rather by superheated air rushing outwards - much of this heating is by X-rays emitted from the bomb during fission. BUt you are correct (at least as far as I recall) that secondary blast effects do occur, including air rushing back towards the explosion through the now rareified atmosphere.

#### ukmicky

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #13 on: 06/05/2007 23:33:42 »
seany
you cant have unstoppable and unmovable one or both would have to give and if was just the moving one that did it would probably atomise.

#### Batroost

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #14 on: 06/05/2007 23:36:32 »
One thing you learn pretty quickly in physics is that there is no such thing as a 'solid' object, let alone an immovable one!

I think a more memorable line is "What's the last thing that goes through a flies mind as it hits your windscreen?"

"It's arse!"

(With apologies to Fly-lovers everwhere)

#### Seany

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #15 on: 06/05/2007 23:39:00 »

#### JimBob

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #16 on: 06/05/2007 23:39:25 »
Look up Newton's laws on Wikipedia Newton's three laws are

First Law

If no external force acts on a particle, then it is possible to select a set of reference frames, called inertial reference frames, observed from which the particle moves without any change in velocity.
Second Law
Observed from an inertial reference frame, the net force on a particle is proportional to the time rate of change of its linear momentum. Momentum is the product of mass and velocity. This law is often stated as F = ma (the force on an object is equal to its mass multiplied by its acceleration).
Third Law
Whenever A exerts a force on B, B simultaneously exerts a force on A with the same magnitude in the opposite direction. The strong form of the law further postulates that these two forces act along the same line.

Einstein came up with E=mC2 or energy = mass x speed of light squared. He proves this by using thought experiments.

HOWEVER - Einstein may not have been the one to come up with it. His first wife, also a theoretical physicist, may have been the originator. I watched a show about his papers, which after the death of his long time secretary, became the property of an Israeli University recently. The program was on the Discovery Science Channel. If you give me a minute or two to look for it, I will try to find a reference or a link to that program.

Forgive me, I never learned to type so I'm still slow. I am up to about 20 words per minute, though!

#### Seany

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #17 on: 06/05/2007 23:44:43 »
Ok.. Thanks. The Third Law, wouldn't that make the moving object bounce back at the same speed?

(I write about 100 words per minute. LOL!)

#### JimBob

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #18 on: 06/05/2007 23:47:34 »
http://dsc.discovery.com/news/2006/07/11/einstein_his.html?category=history&guid=20060711110030

OK, it was SPECULATED by the physicist that the Nobel Prize money was to go to his first wife was because she helped in his relativity formulation. I need to see the program again as I was not totally attentive to this by typing a response to somehting in this site when the physicist said this.

If I am wrong I a wrong

#### another_someone

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #19 on: 06/05/2007 23:48:26 »
What does unstoppable and unmovable actually mean?

There can not be any absolute frame of reference where one thing is regarded as stopped, and another regarded as moving.  All motion is relative.  A thing is only stopped, or only moving, in relation to some particular observer.

To say something is unmovable is merely to say that the particular observer will be in a permanently fixed position with regard to that object - other observers might still see that object as moving.

I assume when you talking about an unstoppable object, you actually mean more than merely unstoppable, but an object which cannot alter its speed relative to you at all (e.g. it has some of the attributes of light travelling through a vacuum).  If all you mean by unstoppable is that it can never have zero velocity relative to you, but is quite capable of bouncing back the way it came, then that does not of itself in any way preclude the immovable object (although there would be other physical laws that would make the idea of an immovable object rather difficult).

#### Seany

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #20 on: 06/05/2007 23:48:36 »
Hmm.. Einstein that lil cheater! LOL

#### JimBob

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #21 on: 06/05/2007 23:49:48 »
My type of guy but not an example for his sons!

#### Seany

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #22 on: 06/05/2007 23:50:28 »
What does unstoppable and unmovable actually mean?

There can not be any absolute frame of reference where one thing is regarded as stopped, and another regarded as moving.  All motion is relative.  A thing is only stopped, or only moving, in relation to some particular observer.

To say something is unmovable is merely to say that the particular observer will be in a permanently fixed position with regard to that object - other observers might still see that object as moving.

I assume when you talking about an unstoppable object, you actually mean more than merely unstoppable, but an object which cannot alter its speed relative to you at all (e.g. it has some of the attributes of light travelling through a vacuum).  If all you mean by unstoppable is that it can never have zero velocity relative to you, but is quite capable of bouncing back the way it came, then that does not of itself in any way preclude the immovable object (although there would be other physical laws that would make the idea of an immovable object rather difficult).

I don't clearly understand.. From every perspective, surely a "stopped" object looks "stopped"?

There is a box. Two people are here. One is moving. The other is still. Both people can see the box. Both people think the box is still?

#### Soul Surfer

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #23 on: 07/05/2007 00:20:44 »
The question is not realistic and therefore not interesting a far more interesting result is what happens when two bodies of similar mass collide exactly in line with their centres and there is very little loss (like billiard balls)  Assume one is stationary and one is moving.  The one that is moving stops dead and the one that was stationary moves on at the same speed as the one that was moving.

#### another_someone

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##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #24 on: 07/05/2007 00:24:37 »
Stopped and moving with respect to what?

There is a box (no windows) that is sitting atop a moving train.  One person within the box is running towards the rear of the train at exactly the same speed as the train is moving forward (and so is stationary with regard to the ground beneath the train), while the other person sitting on a chair in the box (so is stationary with regard to the box, and the train; but is moving forward with regard to the ground).  So who is stationary and who is moving?

#### The Naked Scientists Forum

##### Unstoppable object (moving), Unmoveable object (Still)
« Reply #24 on: 07/05/2007 00:24:37 »