| Topic: |
Science > Physics |
| User: |
"Externet" |
| Date: |
17 Jan 2005 10:41:03 AM |
| Object: |
Force and motion... |
Hello.
Applying a propulsion force to the moon will change its orbit or not ?
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| User: "Uncle Al" |
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| Title: Re: Force and motion... |
17 Jan 2005 01:05:56 PM |
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Externet wrote:
Hello.
Applying a propulsion force to the moon will change its orbit or not
The moon's orbit is constantly changing from tidal dissipation (and
impingement of solar photons). The whole solar system is chaotic not
equilibrium. Pray for minima.
Google
"lunar laser ranging" 9080 hits
--
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: "Puppet_Sock" |
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| Title: Re: Force and motion... |
17 Jan 2005 11:14:21 AM |
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Externet wrote:
Hello.
Applying a propulsion force to the moon will change its orbit or not
?
Yes, of course. F=ma after all. Now ask "how much?"
Socks
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| User: "Externet" |
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| Title: Re: Force and motion... |
17 Jan 2005 11:28:43 AM |
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Hi. Thanks for replying.
You expect a "how much?" ... Let's change it to how long?
A comparatively small force applied to the moon, if sustained long
enough, will then change its orbit.
Actually, ANY propulsion force even a small one, will cause an
proportionally small change of orbit.
Will it?
To continue, step by step...
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| User: "Old Man" |
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| Title: Re: Force and motion... |
17 Jan 2005 05:30:15 PM |
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"Externet" <externet@inorbit.com> wrote in message
news:1105982923.290570.248130@z14g2000cwz.googlegroups.com...
Hi. Thanks for replying.
You expect a "how much?" ... Let's change it to how long?
A comparatively small force applied to the moon, if sustained long
enough, will then change its orbit.
Actually, ANY propulsion force even a small one, will cause an
proportionally small change of orbit.
Will it?
To continue, step by step...
An orbit is uniquely defined by its total energy, E, and its
orbital angular momentum vector, L.
Whilst conserving orbital angular momentum, the orbit's
energy can be altered via a radial impulse.
Whilst conserving energy, the orbit's angular momentum
can be altered with torque and radial impulses combined,
such that, at a given point, orbital speed is maintained
under a change in orbital velocity direction.
[Old Man]
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| User: "John Schoenfeld" |
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| Title: Re: Force and motion... |
17 Jan 2005 05:51:47 PM |
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Puppet_Sock wrote:
Externet wrote:
Hello.
Applying a propulsion force to the moon will change its orbit or
not
?
Yes, of course. F=ma after all. Now ask "how much?"
Socks
F = dp/dt. The difference is important.
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| User: "Sam Wormley" |
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| Title: Re: Force and motion... |
17 Jan 2005 11:30:39 AM |
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Externet wrote:
Hello.
Applying a propulsion force to the moon will change its orbit or not ?
Orbital Perturbation
http://scienceworld.wolfram.com/physics/OrbitalPerturbation.html
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| User: "The Ghost In The Machine" |
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| Title: Re: Force and motion... |
18 Jan 2005 12:01:37 AM |
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In sci.physics, Externet
<externet@inorbit.com>
wrote
on 17 Jan 2005 08:41:03 -0800
<1105980063.489262.62580@f14g2000cwb.googlegroups.com>:
Hello.
Applying a propulsion force to the moon will change its orbit or not ?
Oh it'll change its orbit all right; the question is how much.
Moon mass is 7.35 * 10^22 kg. If one can benchpress
300 pounds (actually, that's the force 136 kg exerts
on Earth, or 1,335 N) for 30 seconds, one gets a total
exertion of about 40,050 N-seconds. (I say "exertion"
instead of "energy" for a reason, though there are some
issues regarding muscular contraction [not to mention
units]; one might get very tired after a time pushing on a
nonmoving wall, but one is doing no work from a mechanical
standpoint.)
If one can -- somehow -- brace oneself a la Archimedes,
the exertion of 1,335 N for 30 seconds on a mass of 7.35 *
10^22 kg will change its velocity by about
30 * (1335 / (7.35*10^22)) = 5.449 * 10^-19 m/s
If the moon is allowed to drift afterwards for 10 years,
the course change is 1.720 * 10^-10 m -- less than
the diameter of a copper atom (2 * 10^-10 m).
Woo.
--
#191,
It's still legal to go .sigless.
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| User: "Externet" |
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| Title: Re: Force and motion... |
18 Jan 2005 04:04:34 PM |
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OK.
Next step: A propulsion rocket, transported to and assembled
vertically upside down on the moon surface, pushing at the moon equator
away from earth with the millions of pounds force for the about 4
minutes the fuel lasts.
The moon will shift somewhat its orbit outwards those 4 minutes and
then describe a larger diameter orbit or will its orbit continue to
spiral away outwards after the fuel is spent?
Thanks.
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