Question

A spaceship is launched from the Earth's surface with a speed v. The radius of the Earth is R. What will its speed be when it is very far from the Earth? (Use any variable or symbol stated above along with the following as necessary: G for the gravitational constant, m for the mass of the spaceship, and M for the mass of the Earth.)

Answer 1

I bet this has to do with energy.

The PE of at the surface of Earth is -GMm/R, if it has KE, 1/2 mv^2, they add to give total energy.

Well total energy= finaltotal energy
1/2mv^2-GMm/R=0PE + Ke

KE at infinity= 1/2 mv^2-GMm/R

YOu may find this interesting:http://www.physlink.com/education/askexperts/ae158.cfm

Answer 2

Thanks Bob. However, I had already tried 1/2mv^2-GMm/R before posting this and it came back as wrong. I'm not sure why it is wrong.