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Blacky372
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Hey guys, we just had a physics test and one exercise was the following:
The Earth pulls down on stuff with 9.81 N/kg.
How strong is this force on the moon?
Radius of the Earth re = 6,370km
Ratio between re and rm = 11:3
Ratio between me and mm = 81:1
Gravitation formula. [itex]F=\gamma*\frac{mM}{r^{2}}[/itex]
In the test I got the correct result ~1,622[itex]\frac{m}{s^{2}}[/itex] but now I can't figure out how I did it.
This is my attempt:
http://imgur.com/4TfyD2G
My formula was basically this:
[itex]F=6.67\cdot10^{-11}\frac{Nm^{2}}{kg^{2}}\cdot\frac{1kg\cdot\frac{9.81N\cdot6.37\cdot10^{6}m}{6.67\cdot10^{-11}\frac{Nm^{2}}{kg^{2}}}:81}{(6.37\cdot10^{6}m\cdot\frac{11}{3})^{2}}[/itex]
EDIT: Okay this is kind of illegible. This one is better: http://i.imgur.com/O6nEQyr.png
I first thought I was right but when i calculate the result its something like 2,72N instead of 1,622N.
How can I get to the right solution?
The Earth pulls down on stuff with 9.81 N/kg.
How strong is this force on the moon?
Homework Statement
Radius of the Earth re = 6,370km
Ratio between re and rm = 11:3
Ratio between me and mm = 81:1
Homework Equations
Gravitation formula. [itex]F=\gamma*\frac{mM}{r^{2}}[/itex]
The Attempt at a Solution
In the test I got the correct result ~1,622[itex]\frac{m}{s^{2}}[/itex] but now I can't figure out how I did it.
This is my attempt:
http://imgur.com/4TfyD2G
My formula was basically this:
[itex]F=6.67\cdot10^{-11}\frac{Nm^{2}}{kg^{2}}\cdot\frac{1kg\cdot\frac{9.81N\cdot6.37\cdot10^{6}m}{6.67\cdot10^{-11}\frac{Nm^{2}}{kg^{2}}}:81}{(6.37\cdot10^{6}m\cdot\frac{11}{3})^{2}}[/itex]
EDIT: Okay this is kind of illegible. This one is better: http://i.imgur.com/O6nEQyr.png
I first thought I was right but when i calculate the result its something like 2,72N instead of 1,622N.
How can I get to the right solution?
Last edited: