Item NG090002: Assuming no energy transfer between a ball and the track it is moving in, the speed of the ball will be the same before and after rolling over a hill because the total amount of energy in the system does not change.

Imagine a ball on a track where no energy is transferred between the ball and the track or between the ball and the air around it.  It is going fast enough at Position 1 so that it will go over a hill on the track and past Position 2.  Position 1 and Position 2 are at the same height.

Will it be going faster, slower, or at the same speed at Position 2 compared to Position 1 and why?  (Remember that no energy is transferred between the ball and the track or between the ball and the air around it.)

1. Faster, because new energy in the form of motion energy (kinetic energy) was made when the ball went down the steep side of the hill
2. Slower, because motion energy (kinetic energy) was used up when the ball went up the long side of the hill
3. The same speed, because the amount of motion energy (kinetic energy) that the ball has remained the same the entire time it was moving along the track
4. The same speed, because the total amount of energy in the system (ball and track) did not change as the ball moved along the track

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