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A space craft of mass 5.9×104 kg is in orbit around a planet of 5.1×1024 kg. If the planet can be assumed to be a uniform sphere of radius 5.4×106 m and the space ship is orbit a height of 6.9×105 m above the surface what is the gravitational potential energy of the ship? [G=6.674×10-11 Nm2kg-2]
. ]3 t5 v( |9 H9 k- a( t. L4 B9 a% M+ v- e' l) Y: [" y* M
[Specify units of 'J', 'kJ', 'MJ' or 'GJ' in your answer.]
2 b) C" f, B) m s4 d7 m( k8 h, E, e6 d. K2 d `# r, L) O2 l
) w* v% ?* t2 `2 n/ l! ~, s: e( M; [
so far what I have done is used the equation for GPE6 Y$ B2 j, W Q+ C$ W) v/ k: _
which is
) U! |" s- u1 w, B lU = - (G me m) / r' c n' B) {8 L6 Z! k: [3 V# x
! S) l P( e& M) P( A( y
where G is 6.674e-11 Nmkg-23 O% w0 p3 v; [( l
me is the mass of the planet 5.1e24 kg $ `2 z! }5 p( D& q. `& F0 n
m is the mass of the space ship 5.9e4 kg r& t: u3 @7 z# z2 o! h* e
r is (i think) the radius of the planet (5.4e4 m) added to the height of the space ship is above the planet (6.9e5 m) and then divided it into G me m |
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发表于 2009-11-10 21:41
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3 O9 g! {; m& a+ B0 B3 }# J% i