An object of mass 1.6 kg is dropped from a height of 2.9 metres. It lands with a speed of 2.8 m/s. How much energy was lost due to air resistance? (Give your answer to 2 s.f., expressed as a magnitude)
How much energy should it have?
m g h = 1.6 * 9.81 * 2.9
How much does it have?
(1/2) m v^2 = (1/2) * 1.6 * (2.8)^2
so subtract