A 100 kg roller coaster car is located at the top of a hill where the height is 20 m. What is the velocity when it reaches the bottom of the hill?

Assuming the coaster’s gravitational potential energy becomes kinetic energy with negligible friction, use mgh = ½mv². The mass cancels, so v = √(2gh) = √(2 × 9.8 × 20) ≈ 19.8 m/s. The correct choice is 19.8 m/s.

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