roller coaster has a mass of 425 kg. It sits at the top of a hill with height of 66 m. How fast is it going when it reaches the bottom?

36 m/s

Explanation:

Gravitational potential energy at top = kinetic energy at bottom

mgh = 1/2 mv²

v = √ (2gh)

Given h = 66 m:

v = √ (2 * 9.8 m/s² * 66 m)

v = 36.0 m/s

Rounded to two significant figures, the roller coaster reaches a speed of 36 m/s.

36 like the other guy said