A satellite of negligible mass compared to a planet of mass moves in a stable…
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A satellite of negligible mass compared to a planet of mass M moves in a stable circular orbit of radius r.
Throughout one complete revolution, the satellite’s kinetic energy K, gravitational potential energy U, and total mechanical energy E remain constant in magnitude (although the satellite continuously changes position).
(a) Describe and explain the sign (positive, negative, or zero) of each quantity K, U, and E for the satellite in its orbit.
(b) The orbital radius is slowly increased to 2r while maintaining a circular path. Qualitatively describe how the magnitudes of K, U, and E each change, and explain why.
(c) During the transition from radius r to 2r, energy must be supplied or removed from the satellite–planet system. Identify the form of energy transfer that occurs and justify your answer in terms of changes to K and U.