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Author Topic: In Space..no one can feel your weight !!  (Read 8963 times)

Offline neilep

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In Space..no one can feel your weight !!
« on: 20/09/2006 21:58:54 »
Hello,

If I was attached nice and securely onthe end a pole that was attached to the moon....... and the pole was long enough so that there would be no gravitational influence at the end where I am attached....would I be able to push away a building sized object , say for instance, something the size of St Pauls Cathedral as easy as if I was pushing away a car sized object  ?

If not ..why not ?

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« Last Edit: 20/09/2006 23:02:34 by neilep »


 

Offline Soul Surfer

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Re: In Space..no one can feel your weight !!
« Reply #1 on: 20/09/2006 23:20:11 »
No, because st paul's cathedral has a lot more mass than a car (and the moon has oodles more mass than st pauls) so you are nicely fixed in place on the end of your long pole.  However if you keep pushing for long enough it would eventually move away and keep moving away.

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Offline neilep

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Re: In Space..no one can feel your weight !!
« Reply #2 on: 20/09/2006 23:49:57 »
THANK YOU IAN

I understand.

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Offline Soul Surfer

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Re: In Space..no one can feel your weight !!
« Reply #3 on: 20/09/2006 23:20:11 »
No, because st paul's cathedral has a lot more mass than a car (and the moon has oodles more mass than st pauls) so you are nicely fixed in place on the end of your long pole.  However if you keep pushing for long enough it would eventually move away and keep moving away.

Learn, create, test and tell
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Offline neilep

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Re: In Space..no one can feel your weight !!
« Reply #4 on: 20/09/2006 23:49:57 »
THANK YOU IAN

I understand.

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Offline bostjan

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Re: In Space..no one can feel your weight !!
« Reply #5 on: 21/09/2006 05:04:03 »
Or it would skewer you on the end of the pole, depending on if it was moving towards you to begin with.
 

Offline lightarrow

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Re: In Space..no one can feel your weight !!
« Reply #6 on: 21/09/2006 08:27:12 »
quote:
Originally posted by bostjan

Or it would skewer you on the end of the pole, depending on if it was moving towards you to begin with.

You are so mean! Neil is such a good boy!
 

Offline syhprum

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Re: In Space..no one can feel your weight !!
« Reply #7 on: 21/09/2006 16:29:54 »
I am at a loss to see how this experiment can be set up!, Is the St pauls mass object in geo-stationary orbit around the moon this seems problematical due to the moons slow rotation rate, is it in the gravitational well between the earth and the moon if so the wobble of the moon relative to this line would cause problems.
I am afraid if I was on the funding committee I would not approve this experiment.

syhprum

syhprum
 

Offline neilep

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Re: In Space..no one can feel your weight !!
« Reply #8 on: 21/09/2006 17:15:00 »
Peter, I would hate to pitch you for the funding of this worthwhile and important project :)


What I was trying to do (poorly, I know ) was just establish the fact that I would not be pushing myself back instead of the objects forward, because they are bigger than me. I was also asking to differentiate between weight and mass in the vaccum of space in a weigthless environment.

So, my premise was to establish my stability when pressing upon the objects and to establish the ease to which each object could be pushed.  I could have chosen any two objects but the size difference was important.

So, are you gonna fund me now...I take credit card ! :) This is like being in the Dragons Den !!..Do you watch that program..I love it


ALBERTO..Thank you for saying I'm a good boy ....you are too :)


Bostjan
...I'm sure I'd make a nice kebab !! :)

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Offline lightarrow

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Re: In Space..no one can feel your weight !!
« Reply #9 on: 22/09/2006 15:03:46 »
Let's make a little computations.
I don't know how much the St Pauls Cathedral could weigh, but, let's say it could be around 10,000 tons (if it's not St Pauls Cathedral, it would be another body with this weight). 10,000 tons = 10^7 Kg.

Let's say that you push it with your legs and that you can do it with a 50 Kgp force ~ 500 N. The body's acceleration would be a = F/m = 500/10^7 = 5*10^(-5) m/s^2.

If you could be able to maintain this push constantly for an entire day ~ 100,000 seconds, then the body would acquire a speed of v = a*t =  5*10^(-5)*100,000 = 5 m/s = 18 Km/h.

The body's momentum p and its kinetic energy E would be:

p = 5*10^7 Kg*m/s
E = 1.25*10^8 Joule.
« Last Edit: 22/09/2006 15:08:07 by lightarrow »
 

Offline neilep

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Re: In Space..no one can feel your weight !!
« Reply #10 on: 22/09/2006 15:06:49 »
YAYYYYYYYY !!!..Thanks Alberto

I'll start exercising my leg muscles now !!

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Offline lightarrow

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Re: In Space..no one can feel your weight !!
« Reply #11 on: 22/09/2006 15:10:28 »
Ok, but, please, don't throw that body against us on earth!!!
 

Offline neilep

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Re: In Space..no one can feel your weight !!
« Reply #12 on: 22/09/2006 15:44:20 »
LOL.....Of course not....ill push it in orbit and we'll have two moons !!

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Offline Karen W.

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Re: In Space..no one can feel your weight !!
« Reply #13 on: 23/09/2006 12:12:09 »
quote:
Originally posted by lightarrow

Let's make a little computations.
I don't know how much the St Pauls Cathedral could weigh, but, let's say it could be around 10,000 tons (if it's not St Pauls Cathedral, it would be another body with this weight). 10,000 tons = 10^7 Kg.

Let's say that you push it with your legs and that you can do it with a 50 Kgp force ~ 500 N. The body's acceleration would be a = F/m = 500/10^7 = 5*10^(-5) m/s^2.

If you could be able to maintain this push constantly for an entire day ~ 100,000 seconds, then the body would acquire a speed of v = a*t =  5*10^(-5)*100,000 = 5 m/s = 18 Km/h.

The body's momentum p and its kinetic energy E would be:

p = 5*10^7 Kg*m/s
E = 1.25*10^8 Joule.



These kind of calculations amaze me its like looking at a foriegn language. I never understood math and equations like this... Sorry, It is off subject but facinating... I am glad someone gets it! I don't but  I am amazed.. It's all over my head! Congrats to you!!

Karen
« Last Edit: 24/09/2006 20:36:43 by Karen W. »
 

Offline lightarrow

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Re: In Space..no one can feel your weight !!
« Reply #14 on: 24/09/2006 12:39:55 »
Thank you. I'm a bit sorry for the fact I wasn't able to make you understand well those equations and computations. If you want, you can ask me what you don't understand completely in them and I'll be glad to explain you.
 

Offline neilep

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Re: In Space..no one can feel your weight !!
« Reply #15 on: 24/09/2006 19:02:54 »
Karen !!..well you know what score I got in the physics test...if those equations were over your head by a few feet...they were a thousand miles in orbit above mine !!! LOL.............. BIG RESPECT to the Alberto Man.

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Offline Karen W.

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Re: In Space..no one can feel your weight !!
« Reply #16 on: 24/09/2006 20:29:51 »
No kidding huh!! Me too! You know Sir.. I only scored a tad higher then you.. I was after all just ribbing you... as it is so much fun....to do!! Your always a good sport and I like the way you "sulk" and "LE SIGH!" Too funny....LOL Ditto on the respect amazing to see someone do that, I have nevr been able to and I picked up this new math book to study for my math classes that I have yet to complete... and wow, it looks like a foreign language and I don't have a clue, I am still in basic level math at about 11th grade leval..46 years old and  I can't do geometry, algebra, trigonometry or any of that lovely stuff. Basic addition subtraction multiplication and division or else lock me up and throw out the key its all wasted on me until I can re- educate myself to learn it!! Yikes scary! I am not going back to school this fall as health dictates but come spring will be back hard at it!! Sometimes I think I was crazy to wait until my kids were grown to go to college! What was I thinking??

Neil you are never to old to bone up Sir... granted I'll give you the tiered thing but do it when you can't sleep, I have been studing my french at night when posting to you all I have 3 different french programs playing in my ears in the evening.. wanted to brush back up.. and hope some day to take a trip and be able to use it!!

Karen
« Last Edit: 24/09/2006 20:44:28 by Karen W. »
 

Offline syhprum

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Re: In Space..no one can feel your weight !!
« Reply #17 on: 24/09/2006 21:53:34 »
I think one of the reasons why some people have difficulty in following what is basicly very simpe arithmetic is the problem of writing it down in the word editor available here.
although people used to the shorthand used find it easy to follow I think if we are to have everyone understand it we should use more of a junior school style

syhprum
 

Offline neilep

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Re: In Space..no one can feel your weight !!
« Reply #18 on: 24/09/2006 23:15:35 »
quote:
Originally posted by syhprum

I think one of the reasons why some people have difficulty in following what is basicly very simpe arithmetic is the problem of writing it down in the word editor available here.
although people used to the shorthand used find it easy to follow I think if we are to have everyone understand it we should use more of a junior school style
syhprum



Amen to that !!..and I'm not even religious !! :)

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Offline Karen W.

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Re: In Space..no one can feel your weight !!
« Reply #19 on: 24/09/2006 23:32:20 »
Yes sir do I agree with that ! would be nice indeed! Its going to take me years to understand all of those equations, as I do not understand the math concept part.. Albetto, could you say that in terms for the likes of me without the equations.. maybe just smething that weighs this much against what? I don't know what all of these represent there fore I am lost in space somewhere in the outer limits!

p = 5*10^7 Kg*m/s
E = 1.25*10^8 Joule.

Karen
« Last Edit: 24/09/2006 23:39:00 by Karen W. »
 

Offline lightarrow

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Re: In Space..no one can feel your weight !!
« Reply #20 on: 25/09/2006 03:25:35 »
You mean what these means?
quote:
p = 5*10^7 Kg*m/s
E = 1.25*10^8 Joule
Or the concept of momentum and kinetic energy?

You know that * means multiplied, I imagine. 10^7 means: 1 followed by seven zeros: 10000000. So, 5*10^7 means: 5 multiplied 10000000 = 50000000 = 50,000,000 = 50 millions.

Momentum p, also called "quantity of motion" is m*v where m is the mass and v the velocity. Momentum is important, for example because the more a body's momentum, the more difficult it is to stop it (or to accelerate it to that speed): you can stop much more easily a 100 grams ball travelling at 50 Km/h than a lorry with the same velocity (because the mass m is greater), as well as it's easier to stop a low velocity ball than the same ball travelling at high velocity (in this case, because the velocity v is greater).

Kinetic energy is the amount of energy you have to give to that body to put it in motion at that speed: E = (m*v^2)/2, or, the amount of energy that body gives back when it is stopped.
 

Offline Karen W.

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Re: In Space..no one can feel your weight !!
« Reply #21 on: 25/09/2006 07:44:34 »
Okay, I think I get it, sort of at least what all the symbols represent now, ..heres where Im getting stumped now, how do I determine "velosity" or the  kenetic energy out put? Don't I need that in order to get the velocity so that one can finish the equation? Does that make sense or am I drowning here??

Karen
 

Offline lightarrow

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Re: In Space..no one can feel your weight !!
« Reply #22 on: 25/09/2006 14:34:09 »
velocity = space/time. You look into your clock how much time the body or you take to cover s meters and you divide them: if you take 20 seconds to cover 500 meters, then your average velocity is 500/20 = 25 meters/seconds = 25 m/s. If you want it in Km/hours, multiply by 3.6: 25*3.6 = 90 Km/h.

This is called "average" velocity because, during those 20 seconds you could have accelerated to more than 90 Km/h or decelerated to less than it. The shorter the time interval, the more you are confident your velocity don't varies. At the limit, for a time interval extremely small, you can say that is your "istantaneous" velocity.

Once you have the velocity v, knowing the mass m, you can compute the kinetic energy E: E(kinetic) = m*v*v/2 = m*v^2/2.

For nitpicking people: that formula for kinetic energy is not valid any longer in relativity (that is, at very high speeds); it's not valid, e.g., for particles in a particle accelerator.
« Last Edit: 25/09/2006 14:39:57 by lightarrow »
 

Offline Karen W.

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Re: In Space..no one can feel your weight !!
« Reply #23 on: 25/09/2006 19:09:55 »
That is complicated but I see it would just have to really concentrate on the whole thing for a while.. Alberto, are you a teacher, cause if your not, you missed your calling!! I teach preschool but nothing like this... Yikes you do a good Job!

Karen
 

Offline lightarrow

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Re: In Space..no one can feel your weight !!
« Reply #24 on: 25/09/2006 19:32:44 »
Thank you Karen (virtual kiss to you). Actually I work as technician in the Sanity Department, but, sometimes, I give private lessons of mathematichs, physics and chemistry to high school students.

I found these sciences so fascinating, that it's a pity they are often taught in a boring or complicated way, at school.

I had the lucky to find, at school, one teacher of physics who liked to make experiments more than theoretical lessons (which are however important!). It's really much more valuable.
 

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Re: In Space..no one can feel your weight !!
« Reply #24 on: 25/09/2006 19:32:44 »

 

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