A 64 kg student traveling in a car with a constant velocity has a kinetic energy of 1.6 10^4 J. What is the speedometer reading of the car in km/h?

Answer 1

(1/2) m v^2 = 1.6*10^4
32 v^2 = 160 * 10^2
v^2 = 5 * 10^2
v = 10 sqrt 5 or about 22.4 m/s
22.4 m/s *3600 s/h * 1 km/1000 m
= 80.5 km/h