Help me with physics?

To solve that, you need to find the formula for the potential energy due to gravity. The formula for the gravitational force is: F = G m1 m2 / r^2, where G is the gravitational constant, m1 is the mass of the shuttle, m2 is the mass of the Earth and r is the distance between the shuttle and the *center* of the Earth. You can get from force to potential energy, V, by integrating, because of the relation F = - d/dr V. That will get you V = G m1 m2 / r. To find the energy required to boost the shuttle to the new orbit, you calculate the potential energy at a height of 250km and at 650km. The difference between those two potential energies is the energy required to reach the new orbit.