physics
posted by Rachel on .
A 981kg satellite orbits the Earth at a constant altitude of 103km.
How much energy must be added to the system to move the satellite into a circular orbit with altitude 199 km?
I need answer in MJ
please tell me what formula

find the original PE+KE
find the new PE+KE
what is the difference? 
You need to do work against gravity to move it to a higher orbit, but you get some back because the kinetic energy will be less at the higher orbit. You have to consider the total energy required.
The total energy (kinetic + potential) for a circular orbit at radius R is
Etotal = (1/2) m V^2  G M m/R
where G is the universal constant of gravity and M is the mass of the Earth. Since
V^2/R = GM/R^2,
Etotal = (1/2)m*GM/R GmM/R
= (1/2)GmM/R
Compute this quantity at R = 103 km and at R = 199 km and take the difference. The work required will be positive. 
ok sir is the formula
(1/2)GmM/R