Kinetic and Potential energy sort of fight with each other as a roller coaster<span> moves. As it rolls </span>downhill<span>, it loses potential energy because it's getting closer to the ground, but gains kinetic energy because it begins to move faster</span>
The heat transfer in this event is through physical contact, there are other ways to transfer heat (radiation, convection etc.)but in this case. The channel or mode of heat transfer is through surface contact. Thus when the surface of the metal ball comes in contact with the ice block. Only portion is actually in contact.
I would think both because you cannot predict what will happen because it is unbalanced you are basically letting the earth take control of the object.
hope that helped?!
:)