- #1

jakeginobi

## Homework Statement

At a circular orbit and at an elliptical orbit when do I use 1/2mv^2 instead of the kinetic equation from which I derived from F=GMm/r^2 which is Ek = GMm/2r

## Homework Equations

F=GMm/r^2, Ek = GMm/2r,

Ek = 1/2mv^2

## The Attempt at a Solution

For instance, when I tried to use the other kinetic energy equation (GMm/2r) to solve the kinetic energy of a satellite at perigee, it gave a totally different answer if I use 1/2mv^2