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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]# S4 s: h5 T) S3 i. K" e
% g: T! E' w5 C
[Specify units of 'J', 'kJ', 'MJ' or 'GJ' in your answer.]0 Y+ w+ f+ M) r# w' \
' j Z) ~$ p8 G
, z, g8 d5 e1 b/ |6 Bso far what I have done is used the equation for GPE" ^. y6 r8 ^/ t- ^! R6 g$ t* c+ C
which is
4 b* }. F- f) ~U = - (G me m) / r; N! C* C3 B2 ^) ^
6 q$ ~9 ^+ d& @0 n! e( b
where G is 6.674e-11 Nmkg-2; i N' J4 c1 u6 Z
me is the mass of the planet 5.1e24 kg 1 l. q3 X7 P, c
m is the mass of the space ship 5.9e4 kg
$ g2 @2 ]: R. F' Qr 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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8 F3 ^0 X0 w+ W! ^8 s* q) P