In an elliptical orbit, a satellite has the greatest speed when it is closest to the earth, and the least speed when it is furthest from the earth. Total energy is constant and the potential energy doesn't change, so the kinetic energy can't change. In an elliptical orbit the potential energy does change while the total energy doesn't change. Thus the kinetic energy must also change. Potential energy is smallest when the satellite is closes to the earth, the perigee.
Potential energy is largest when the satellite is farthest from the earth, the apogee.
Inertia keeps the moon from crashing into the earth. Inertia would keep the moon moving in a straight path and it would leave the earth. Instead, gravity pulls the moon towards the earth just enough to bend its path to follow the earth s curvature 19. The sketch would have the second figure with the satellite s orbit and the earth. The arrow showing the force would be the same.