A 1000 kg boulder sits at the top of a 50-meter high cliff. Determine the amount of potential energy possessed by the boulder if the acceleration due to gravity is 9.8 m/s2. The boulder has(magnitude/ number)(units) of Potential Energy.

This is kenetic energy.

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other