Quick question about gravity

General physics and astronomy discussions not directly related to Celestia
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Danial
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Quick question about gravity

Post #1by Danial » 21.10.2008, 02:44

I was just wondering, if you were standing on a planet with half the gravity of Earth, would that mean you could jump twice as high or is it not that simple a calculation?

MKruer
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Re: Quick question about gravity

Post #2by MKruer » 21.10.2008, 07:25

Short answer is yes.

Not so short, It depends on atmosphere conditions which goes in resistance from the atmosphere, also there will be a maximum speed at which you can push off the ground (jump) which will also limit how high you can jump.

Edit:
http://weblog.fortnow.com/2007/03/jumping-in-space.html

For the Moon with is 1/6 the gravity
(6F/Mg -1)/(F/Mg-1)
F= Force
M = Mass
g = Gravitational constant

If it were on Pluto you would weight 1/15
so the equation would be
(15F/Mg -1)/(F/Mg-1)

Hope that makes sense

SU(3)xSU(2)xU(1)
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Re: Quick question about gravity

Post #3by SU(3)xSU(2)xU(1) » 21.10.2008, 09:41

Danial wrote:I was just wondering, if you were standing on a planet with half the gravity of Earth, would that mean you could jump twice as high or is it not that simple a calculation?

Danial,

It is really simple. Imagine, that you try to jump as high as you can, so you try to put the maximal amount of energy in the jump. This energy is always the same (on all planets, moons etc.). When you are at the maximal height during the jump, this energy is just your potential energy in the gravitational field (I neglect some small energy loss). There is a simple formula for potential energy:

[tex]E_{p} = m g h[/tex]

You can see, that if the energy [tex]E_{p}[/tex] and your mass [tex]m[/tex] are constant (as in this case), the height [tex]h[/tex] is anti-proportional to the gravitational acceleration [tex]g[/tex].

So, the answer to your question is yes :)

Paul
"Physicists know what's important, but they don't know what is true. Mathematicians know what's true, but they don't know what is important."

Topic author
Danial
Posts: 33
Joined: 31.03.2008
Age: 45
With us: 16 years 8 months
Location: Gold Coast, Australia

Re: Quick question about gravity

Post #4by Danial » 21.10.2008, 22:14

Thank you both :)


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