Harris+T+(2009)

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As the coaster gets higher in the air, gravity can pull it down a greater distance.

The potential energy you build going up the hill can be released as kinetic energy.

At the top of the first lift hill, there is maximum potential energy because the train is as high as it gets.

At the bottom of the hill, there is maximum kinetic energy and little potential energy.

The potential-energy level builds as the train speeds to the top of the loop (e), but it is soon converted back to kinetic energy as the train leaves the loop.

­Since an object in motion tends to stay in motion (Newton's first law of motion), the coaster car will maintain a forward velocity even when it is moving up the track, opposite the force of gravity.

If the tracks slope down, gravity pulls the front of the car toward the ground, so it accelerates.

If the tracks tilt up, gravity applies a downward force on the back of the coaster, so it decelerates.