Question

Do I need to put a negative in-front of my final 2 values or do I keep them positive?

Answer 1

Gravitational potential energy at a distance of 700000000 km is

`U_1=(-6.674*10^(-11)*4*10^(22)*5*10)(1)/(700000000)`
`U_1=-1.91*10^(35)\text{ J}`

The gravitational potential energy at a distance of 600000000 km is

`U_2=((-6.674*10^(-11)*4*10^(22)*5*10))/(600000000)=-2.22*10^(35)\text{ J}`

Therefore the difference in the energy is

`\Delta U=U_1-U_2`

i.e.,

`\Delta U=-1.91*10^(35)-(-2.22*10^(35))=0.31*10^(35)\text{ J}`

Therefore the change in the gravitational potential energy is 0.31×10³⁵ J