In a rollercoaster, provided losses of thermal energy because of friction can be neglected, which of the following is true? The mechanical energy decreases as the car moves to the top of the slope. The kinetic energy decreases as the car moves to the top of the slope. The rollercoaster moves at constant speed as its height above the ground increases. The mechanical energy increases as the car moves to the top of the slope. The gravitational potential energy decreases as the car moves to the top of the slope