Problem 1: A car of mass 2 * 10 3 kg travelling at 36 km / hr on a horizontal road is brought to rest in a distance of 50m by the action of brakes and frictional forces. Calculate:( a) average stopping force,( b) Time taken to stop the car
Solution. m = 2 * 10 3 u = 36 km / hr = 10m / s s = 50m v = 0 To find: a, F, t Third equation of motion: v 2 = u 2 + 2as 0 = 100 + 2a * 50 Or, a =-1 m / s 2 Therefore, F = ma =( 2 * 10 3) * 1 = 2 * 10 3 N V = u + at 0 = 10 – t t = 10 sec