Asked by Willismerg

An object of mass 4kg is raised to a point A, 100m above the ground. If its initial potential energy is 4000J, what is its kinetic energy when it falls through a distance of 20m.
Answered by oobleck
loss of PE = gain in KE, so since it has moved down by 20m, that would be
mgh = 4*10*20 = 800 J