| Topic: |
Science > Physics |
| User: |
"Karl Engel" |
| Date: |
17 Feb 2005 06:45:23 AM |
| Object: |
Mass/enertia in weightlessness - cars in space! |
Sorry if this is way too basic for this NG, please suggest where I
should post.
If I'm in a big room in a space station or the bay of the shuttle
(effectively weightless) and there's a car in there (JUST SAY!!!), and
I'm braced against one wall and I push the car over to my other
astronaut pal on the other side... does it crush him because it still
has the *mass* of a car and tremendous enertia coming towards him at
speed, or can he just push it back to me like it was made of
styrofoam?
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| User: "CWatters" |
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| Title: Re: Mass/enertia in weightlessness - cars in space! |
17 Feb 2005 11:39:49 AM |
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"Karl Engel" <karlengel@excite.com> wrote in message
news:e6dc7d48.0502170445.4b741588@posting.google.com...
Sorry if this is way too basic for this NG, please suggest where I
should post.
If I'm in a big room in a space station or the bay of the shuttle
(effectively weightless) and there's a car in there (JUST SAY!!!), and
I'm braced against one wall and I push the car over to my other
astronaut pal on the other side... does it crush him because it still
has the *mass* of a car and tremendous enertia coming towards him at
speed,
Yes but only if he isn't as strong as you. He could brace himself agains his
wall and slow the car down just as "easily" as you pushed it.
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| User: "Dave Langers" |
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| Title: Re: Mass/enertia in weightlessness - cars in space! |
17 Feb 2005 07:06:44 AM |
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Sorry if this is way too basic for this NG, please suggest where I
should post.
If I'm in a big room in a space station or the bay of the shuttle
(effectively weightless) and there's a car in there (JUST SAY!!!), and
I'm braced against one wall and I push the car over to my other
astronaut pal on the other side... does it crush him because it still
has the *mass* of a car and tremendous enertia coming towards him at
speed, or can he just push it back to me like it was made of
styrofoam?
Don't try that at home ;)
The cars inertia is still enormous, as you correctly noticed, so he may
just get crushed. (Why did you think that you need to brace yourself to
push it? That is just the same.)
BTW: You could also say that you are pushing the entire space station,
bracing against the car. A space station surely seems to be an efficient
thing to crush a person with. (Although the effect is still the same of
course.)
--
M.vr.gr.
Dave
("d-dot-langers-at-wxs-dot-nl")
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| User: "Roland Franzius" |
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| Title: Re: Mass/enertia in weightlessness - cars in space! |
17 Feb 2005 07:50:52 AM |
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Dave Langers wrote:
Sorry if this is way too basic for this NG, please suggest where I
should post.
If I'm in a big room in a space station or the bay of the shuttle
(effectively weightless) and there's a car in there (JUST SAY!!!), and
I'm braced against one wall and I push the car over to my other
astronaut pal on the other side... does it crush him because it still
has the *mass* of a car and tremendous enertia coming towards him at
speed, or can he just push it back to me like it was made of
styrofoam?
Don't try that at home ;)
The cars inertia is still enormous, as you correctly noticed, so he may
just get crushed. (Why did you think that you need to brace yourself to
push it? That is just the same.)
Given your meal at morning and much training including some anabole
steroids you will be able to give the car a speed of perhaps 0.1 m/s ~
150 J Energy and your pal will stop it in a mirror movement.
Its just the same situation if you try to kill somebody with a
punchingball of that weight hanging down at a long rope. Try to move it.
--
Roland Franzius
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| User: "Gregory L. Hansen" |
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| Title: Re: Mass/enertia in weightlessness - cars in space! |
17 Feb 2005 01:46:07 PM |
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In article <e6dc7d48.0502170445.4b741588@posting.google.com>,
Karl Engel <karlengel@excite.com> wrote:
Sorry if this is way too basic for this NG, please suggest where I
should post.
No question is too basic for this newsgroup. There's more physics in this
question than in some of the seemingly more advanced discussions around
here.
If I'm in a big room in a space station or the bay of the shuttle
(effectively weightless) and there's a car in there (JUST SAY!!!), and
I'm braced against one wall and I push the car over to my other
astronaut pal on the other side... does it crush him because it still
has the *mass* of a car and tremendous enertia coming towards him at
speed, or can he just push it back to me like it was made of
styrofoam?
It wasn't exactly a peice of styrofoam when you pushed it away. It
probably won't be going very fast. What it does to your partner will
depend on how hard you push, how strong he is, whether he's able to brace
himself and control the car. Not entirely unlike throwing a bowling ball
at someone.
--
"Experiments are the only means of knowledge at our disposal. The rest is
poetry, imagination." -- Max Planck
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| User: "Uncle Al" |
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| Title: Re: Mass/enertia in weightlessness - cars in space! |
17 Feb 2005 09:19:27 AM |
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Karl Engel wrote:
Sorry if this is way too basic for this NG, please suggest where I
should post.
If I'm in a big room in a space station or the bay of the shuttle
(effectively weightless) and there's a car in there (JUST SAY!!!), and
I'm braced against one wall and I push the car over to my other
astronaut pal on the other side... does it crush him because it still
has the *mass* of a car and tremendous enertia coming towards him at
speed, or can he just push it back to me like it was made of
styrofoam?
Kinetic energy is conserved as is momentum. They depend upon mass not
weight.
Gravitational mass (lifting a car) and inertial mass (pushing a car)
are in empirical invariant ratio. Neither is dependent upon perceived
weight. He gets crushed. That is one reason why NASA in particular
and rockets (mass tossers) in general are such bad jokes. Nobody does
any serious traveling in this solar system or beyond uhtil somebody
evolves more useful physics. The /_\(momentum) cost is too high to
diddle action-reaction engines.
m_g/m_i = K
is wonderfully coincident for all possible differences in chemical
comspiton including gravitational binding energy,
<http://wugrav.wustl.edu/people/CMW/update98.pdf>
<http://www.astro.northwestern.edu/AspenW04/Papers/lorimer1.pdf>
Equivalence Principle testing
<http://www.npl.washington.edu/eotwash/pdf/prl83-3585.pdf>
http://arXiv.org/abs/gr-qc/0301024
Nordtvedt Effect
We're looking at m_g/m_i for incommensurable atomic lattice geometry,
http://www.mazepath.com/uncleal/qz.pdf
The proper test of spacetime geometry is test mass geometry.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
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| User: "Mike" |
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| Title: Re: Mass/enertia in weightlessness - cars in space! |
17 Feb 2005 05:19:28 PM |
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Karl Engel wrote:
Sorry if this is way too basic for this NG, please suggest where I
should post.
If I'm in a big room in a space station or the bay of the shuttle
(effectively weightless) and there's a car in there (JUST SAY!!!),
and
I'm braced against one wall and I push the car over to my other
astronaut pal on the other side... does it crush him because it still
has the *mass* of a car and tremendous enertia coming towards him at
speed, or can he just push it back to me like it was made of
styrofoam?
When you push the car, let's say for simplicity from rest wrt the frame
of reference of the station, its momentum changes from zero to P=mv. It
reaches the other guy with that speed.
Now, if the other guy is as strong as you are, he can stand against the
wall and push the car back by applying the same force you did for the
same interval of time.
If you are not lucky and he is stronger than you you may get crashed.
But the car cannot move faster than the change in momentum affected by
the impulse applied on it according to Newton's second law:
/_\P = F/_\t
If you can apply that impulse (right hand side) the other guy can
counter apply it to stop the car.
So the correct answer is nothing happens unless one of you is way
stronger than the other guy and can make the car move at a speed much
above the capability of the other guy.
Mike
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| User: "Sam Wormley" |
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| Title: Re: Mass/enertia in weightlessness - cars in space! |
17 Feb 2005 02:16:59 PM |
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Karl Engel wrote:
Sorry if this is way too basic for this NG, please suggest where I
should post.
If I'm in a big room in a space station or the bay of the shuttle
(effectively weightless) and there's a car in there (JUST SAY!!!), and
I'm braced against one wall and I push the car over to my other
astronaut pal on the other side... does it crush him because it still
has the *mass* of a car and tremendous enertia coming towards him at
speed, or can he just push it back to me like it was made of
styrofoam?
Newton's Second Law applies
http://scienceworld.wolfram.com/physics/NewtonsSecondLaw.html
The motion of a particle (or car) is described by Euler's statement of Newton's
second law, namely
F = ma
Here F is the applied force, m is the mass of the particle, and
a = dv/dt is the particle's acceleration, with v being the particle's
velocity. This equation, together with the principle that bodies act
symmetrically on one another--so that the force particle A feels from
particle B is equal to the force B feels from A--is the basis for
understanding particle dynamics".
"Newton's law completely describes all the phenomena of classical
mechanics...."
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| User: "Sam Wormley" |
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| Title: Re: Mass/enertia in weightlessness - cars in space! |
17 Feb 2005 08:15:48 AM |
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Newton's Second Law applies
http://scienceworld.wolfram.com/physics/NewtonsSecondLaw.html
The motion of a particle (or car) is described by Euler's statement of Newton's
second law, namely
F = ma
Here F is the applied force, m is the mass of the particle, and
a = dv/dt is the particle's acceleration, with v being the particle's
velocity. This equation, together with the principle that bodies act
symmetrically on one another--so that the force particle A feels from
particle B is equal to the force B feels from A--is the basis for
understanding particle dynamics".
"Newton's law completely describes all the phenomena of classical
mechanics...."
.
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| User: "tj Frazir" |
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| Title: Re: Mass/enertia in weightlessness - cars in space! |
17 Feb 2005 12:39:09 PM |
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F is the gain in mass as no object can acelerate without graining mass.
The gain in mass is pushing the mass of the atom. F will allways be
identical to the gain in mass .
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