If a satellite is in a sufficiently low orbit, it will encounter air drag from the earth's atmosphere. Since air drag does negative work (the force of air drag is directed opposite the motion), the mechanical energy will decrease. If E decreases (becomes more negative), the radius r of the orbit will decrease. If air drag is relatively small, the satellite can be considered to be in a circular orbit of continually decreasing radius.

A satellite with mass 2360kg is initially in a circular orbit a distance 330km above the earth's surface. Due to air drag, the satellite's altitude decreases to 250km . find out the initial orbital speed. I got to be 7710 m/s which is right.

find out the initial mechanical energy.

find out the change in kinetic energy.

find out the change in gravitational potential energy.

find out the change in mechanical energy.

find out the work done by the force of air drag