求 一道物理题 12点前

chulinlong

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]

[Specify units of 'J', 'kJ', 'MJ' or 'GJ' in your answer.]
' @$ I) E1 p: _9 c2 S' e: I

so far what I have done is used the equation for GPE
. l* Y) {+ k5 b  N7 }& fwhich is
7 _# V! x' q  Y* w2 e7 R9 PU = - (G me m) / r

: D6 ^( [7 Z+ m% S& Qwhere G is 6.674e-11 Nmkg-2
me is the mass of the planet 5.1e24 kg
m is the mass of the space ship 5.9e4 kg
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

chulinlong

做出来了 谢谢

Maths

+ @1 K9 r( x, a# L. S
用这个公式错了么?
还是说只是纯粹的计算出错?

chulinlong

3# Maths
: |) g7 t3 h" {; P* I3 Y) d$ A
0 O" W4 F7 {/ S: d0 O/ K/ p" q, Z
  w/ U2 L6 s4 N" [2 O3 U这个公式对的