a 60-kg student travelling in a 1000 kg car with a constant velocity has a kinetic energy of 1.2 *10^4 J. What is the speedometer reading of the car in km/h?

Answer 1

KE = 0.5*M*V^2 = 12,000 J.
0.5*60*V^2 = 12000.
V = 20 m/s.

Speed = 0.020km/s * 3600s/h = 72 km/h.