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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]
& N& ]# d. j+ }/ I* i0 _" |" K4 }6 _9 }7 s8 \8 A" B6 e# \. ~
[Specify units of 'J', 'kJ', 'MJ' or 'GJ' in your answer.]
* S( t0 }, Q9 [5 l( K* k3 M- | p
& S, a% l# U4 A2 P- O! T, C" L5 }- a5 Q/ t
so far what I have done is used the equation for GPE9 j9 i; K; k- x& m4 }9 Q0 M" t
which is & S3 B: ~3 A1 m" i
U = - (G me m) / r
! x' | l0 ^; p6 X
4 M/ p5 I' X- H5 _" ~where G is 6.674e-11 Nmkg-2" F0 y! p/ B, A, p/ K* f
me is the mass of the planet 5.1e24 kg ) \5 f/ O( ?( y7 F
m is the mass of the space ship 5.9e4 kg
; C( L1 |" n o- B3 O0 ]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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