A 38kg child is at the top of a slide that is 2.1m tall. If there is no friction, how fast will they be moving when they reach the bottom? How fast if they lost 250.0J of energy?

Answer 1

Potential energy at the top is mgh = 38 x 9.8 x 2.1 J

If no loss of energy this all changes to kinetic energy at the bottom = 0.5 mv²

So 0.5 x 38 x v² = 38 x 9.8 x 2.1, so you can solve this for v.

If they lose 250 J of energy due to friction

0.5 x 38 x v² = 38 x 9.8 x 2.1 - 250, which you can solve for v again