This question came up on a quiz and i got it wrong. a)how much energy does it take to send a 1000kg object from the surface of the earth to a height of 500km above the earth's surface? b) how much energy does it take to put the same object into ORBIT at 500km above the surface of the earth. For part A, i got -4.5*10^9 Joules, but i dont know if thats right. part b is what i really dont understand, so any help here would be appreciated, thanks.