# Where does the potential energy go when mass is lifted out of Earth's gravitational field?

There is a finite amount of energy needed to be spent on a rocket or a rock that is taken out of the Earth's gravitational field. Lets suppose the rock is taken far enough to have no effect of Earth's gravity. What happens to this energy? Who gets this?

Where does this energy go?

Assume that the rock went just outside the gravitational field with zero velocity.

Now.

Lets say at the gravitational boundary ( place were the gravitational effect is very small) you decide to convert the mass of the rock to pure energy. What will be the energy released ? $$E = m c ^ 2$$ or $$E = m c ^ 2 + mgd$$ where d is the distance of the mass from Earth.

• There is no such thing as "just outside the gravitational field". The potential energy is always there were the object to fall back to Earth. Your question is somewhat related to en.wikipedia.org/wiki/Gravitational_binding_energy Commented Feb 18, 2014 at 17:15
• Lets say at the gravitational boundary ( place were the gravitational effect is very small) you decide to convert the mass of the rock to pure energy. What will be the energy released ? $E = m c ^ 2$ or $E = m c ^ 2 + mgd$ where d is the distance of the mass from Earth. Commented Feb 18, 2014 at 19:07

• What happens if you convert the entire bicycle to energy at the top of the mountain? Will it be $E = mc^2 or E = mc^2 + mgh$ Commented Feb 18, 2014 at 19:04