Question

A car of mass 1250 kg is moving at a uniform speed of 72 km/h. On applying brakes it's
speed is reduced to 18 km/hr . Calculate

Answer 1

Answer:

m = 1250kg

u = 72km/h = 20m/s

v = 18km/h = 5m/s

Initial kinetic energy = 1/2mu^2

= 1/2(1250)(20)^2 = 250000J

Final kinetic energy = 1/2mv^2

= 1/2(1250)(5)^2 = 15625J

Change in Kinetic Energy = Final kinetic energy - Initial kinetic energy

= 1/2mv^2-1/2mu^2

= 15625-250000

= -234375J