A roller coaster car is pulled to the top of the first hill by a chain driven by an electric motor. The car is then released. It rolls down the first hill and over a second, lower hill. At the end of the ride, brakes bring the car to rest on a level track.

Explain the changes in the way energy is stored and transferred from the moment the motor starts to pull the car up the first hill until the car stops.

You should refer to conservation of energy in your answer.