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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]. \; `/ k! S$ }, D; Z8 w
/ g' Z5 |6 C% ^! \5 ]+ l% V4 P7 \4 B
[Specify units of 'J', 'kJ', 'MJ' or 'GJ' in your answer.]
8 n; ~1 b' Z7 A. O4 q7 P
: z `$ M: a3 i9 Z) M9 r" j+ j8 w' h& D! k7 Q5 d
so far what I have done is used the equation for GPE4 n; {; S( D; V9 v8 M& d( \, U; o
which is / S6 Z- I: S4 E& A1 ~/ h# ]* S( o S: ?
U = - (G me m) / r
& f' D+ \, `# H6 O# F. T, @7 a5 D/ H3 H* s( [; g# b
where G is 6.674e-11 Nmkg-2% j4 O+ ?8 G+ E7 P0 S; _- w
me is the mass of the planet 5.1e24 kg
) X' s3 x0 x1 I; \% @0 zm is the mass of the space ship 5.9e4 kg
# V( ~& R/ A, _- l6 l& Nr 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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