The driver of a three-wheeler moving with a speed of 36 km/h sees a child standing in the middle of the road and brings his vehicle to rest in 4.0 s just in time to save the child. What is the average retarding force on the vehicle ? The mass of the three-wheeler is 400 kg and the mass of the driver is 65 kg.

Explanation

`a = -2.5 ms^(-2)` , Retarding force ` = 465 xx 2.5 = 1.2 xx 10^3 = N`