Question

Which of the following has a higher kinetic energy?

A 1000 kg car rolling at a speed of 5 m/s across the floor or a 1500 kg hippo swimming at a speed of 2 m/s

(3 points)

the car

the hippo

their kinetic energies are equal

not enough information to determine

Answer 1

Calculate kinetic energy KE = 1/2 m v^2.

Car: KE = 0.5(1000 kg)(5 m/s)^2 = 0.5·1000·25 = 12,500 J
Hippo: KE = 0.5(1500 kg)(2 m/s)^2 = 0.5·1500·4 = 3,000 J

Therefore the car has the higher kinetic energy.