Question

Which runner has greater kinetic energy: a 45 kg runner moving at a speed of 7 m per second or a 93 kg runner moving at a

speed of 3 m/s?

Answer 1

Kinetic Energy = (1/2) (mass) (speed)

First runner: KE = (1/2) (45kg) (49 m/s) = 1,102.5 Joules

Second runner: KE = (1/2) (93kg) (9 m/s) = 418.5 Joules

The first runner has 163% more kinetic energy than the second runner has.