tornado is the answer
the primary difference between, elastic and inelastic collisions is, in elastic collision, kinetic energy is conserved and in inelastic collisions, kinetic energy is not conserved. in inelastic collisions, a part of the kinetic energy is used in the deformation of the bodies.
(i think im spelling it wrong)
an olliptical orbit is a non circular orbit around somethin
your answer is gravity
hope this could : )