Minimum energy to raise vehicle 5.22e6 m above lunar surface

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grantP
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Homework Statement



What minimum energy is required to raise a 1.7e3 kg vehicle from the surface of the moon to a height of 5.22e6 m?

Homework Equations



Ep= -G(m1m2)/r

The Attempt at a Solution



Ep(initial)= -6.67e^-11(1.7e^3 x 7.35e^22)/1.74e^6 = -4789750000

Ep(final)= -6.67^-11(1.7e3 x 7.35e^22)/6.96e^6= -1197437500

I have tried subtracting the final by the initial, but I am not getting the correct answer of 3.6e^9 J.
 
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Hi grantP,

grantP said:

Homework Statement



What minimum energy is required to raise a 1.7e3 kg vehicle from the surface of the moon to a height of 5.22e6 m?

Homework Equations



Ep= -G(m1m2)/r

The Attempt at a Solution



Ep(initial)= -6.67e^-11(1.7e^3 x 7.35e^22)/1.74e^6 = -4789750000

Ep(final)= -6.67^-11(1.7e3 x 7.35e^22)/6.96e^6= -1197437500

I have tried subtracting the final by the initial, but I am not getting the correct answer of 3.6e^9 J.

What are you getting? It looks to me like if you do Ep(final) - Ep(initial) you do get 3.6 x 109J.
 
oh...hmmmm i must have mixed up my signs...and doing 4 straight hours of physics homework probably didnt help...looking back at it 4 hours later I was probabaly so delerious haha.

Well anyways thanks for the help on my threads.
 
Right, I understand completely about how too much work can make you start seeing things. Glad to help!