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