The force we need to apply is the object’s weight, or ( ) and the distance we over which we apply the force is the change in height . Therefore the work we did was: and this must be the same the amoun...The force we need to apply is the object’s weight, or ( ) and the distance we over which we apply the force is the change in height . Therefore the work we did was: and this must be the same the amount that we have changed the gravitational potential energy.