1) A young child holds a ball over the edge of a balcony. The ball possesses gravitational potential energy. The ball is released, falls on to a concrete path below, and bounces back up.

Which sequence represents, in the correct order, the transformations of the gravitational potential energy after the ball is released?

2) The efficiency of an electrical generator is 65 %. The energy input to the generator is 12 kJ. What is the useful energy output?

3) A 300 N force is applied to a box to move it up a ramp, as shown.

How much work is done by the force when moving the box from X to Y?

4) A horizontal force of 90 N is used to push a box across a horizontal floor. The frictional force on the box is 50 N. What is the gain in kinetic energy of the box when it is moved through a distance of 6.0 m?

5) A girl of weight 500 N runs up a flight of stairs in 10 seconds. The vertical height of the stairs is 5 metres.

What is the average power developed by the girl?