For this we need to use a SUVAT equation. S=displacement U=initial velocity V=final velocity A=acceleration T=time In the question we are give U=0m/s since the ball is at rest to start with Since the ball is falling under gravity A=9.8m/s^2 The ball falls 10m so S = 10m We want to calculate V so the equation we use is V^2 = U^2 +2AS U=0 so V^2 = 2AS and V = sqrt(2109.8) = sqrt(196) = 14m/s Note, in this question we set the downwards direction as positive since the final velocity, displacement and acceleration were all in this direction.