4.13 understand how conservation of energy produces a link between gravitational potential energy, kinetic energy and work

An object of mass, m weights mxg newtons. So the force, F, needed to lift is mg. If we raise the object through a distance h, the work done on the object is mgh. This is also the gain of GPE.

When the object is raised, it falls-it loses GPE but gains KE. At the end of the fall, all the initial GPE is converted into KE. And that’s how energy is conserved.

work done lifting object=gain in GPE=gain in KE of the object just before hitting the ground