Question

A roller coaster has a mass of 275 kg. It sits at the top of a hill with height 85 m. If it drops from this hill, how fast is it going when it reaches the bottom?

Answer 1

$41xm/s$

Explanation:

The potential energy of the roller coaster is converted into kinetic energy when it reaches the bottom.

So we can write:

$mgh=\frac{1}{2}m{v}^2$

$\therefore v=\sqrt{2gh}=\sqrt{2\times 9.8\times 85}=41m/s$

As you can see, the mass given is irrelevant to the question.