Trent builds a model electric motor. when he connects a battery to the motor, the motor spins through a half rotation and stops. which is the most likely solution to the problem?

answer checking the commutator, because the current is not reversing

This energy transformation diagram represents the energy of a skateboarder moving along a half-pipe. as she skates toward the top of the half-pipe, her original kinetic energy is converted to potential energy and friction. how much of the energy is potential?