GCSE Questions: Energy Changes

Q8. The diagram shows Lana about to dive off a diving board.

(a) Lana has energy by virtue of her position and due to her speed of movement.

As she falls towards the water:

(i) name the type of her energy that decreases Potential gravitational energy

(ii) name the type of her energy that increases Kinetic energy

[2 marks]

(b) At the instant the diver hits the water, her kinetic energy is 5040 J.

If her speed is 12 m/s, calculate her mass.

Kinetic energy = E_k

E_k = ½mv²

5040 = ½ x m x 12²

m = 5040 x 2/144

m = 70 kg

[4 marks]

(c) When she hits the water an energy transfer occurs. Most of the kinetic energy of the diver is transferred to the water.

How does this affect the thermal energy of the water?

The thermal energy increases - the temperature of the water rises - the water gets hotter.

[1 mark]

[Total 7 marks]