Question

For launching a satellite into orbit around earth, would the proper conservation of energy formula be: Epi + Eki + O work = Epf + Ekf? Would work = 0 for launching a satellite? And, would Epi = -Gm1m2/radius of earth or would it just equal 0 (because we usually set Ep on earth's surface to equal 0). Thanks!

Answer 1

Work is definitely not zero for launching a satellite. The kinetic energy must increase to reach orbital velocity. The potential energy also increases because you are raising it farther above the Earth's surface.

The formula Epi = -G*m1*m2/R can be used for the potential energy, if m1 is the mass of the Earth and R is the radius of the orbit (or of the earth, at launch)

The potential and kinetic energy increases needed for launch are roughly the same, as I recall. See
http://physics.info/orbital-mechanics-2/practice.shtml