A car is moving with a uniform velocity of 30 m s-1 . It is stopped in 2 s by applying a force of 1500N through its brakes . Calculate
1. The change in momentum of the of the car.
2. The retardation produced in the car.
3. The mass of the car
Dear Student
Given:
Initial velocity = 30 m/s
Final velocity = 0 m/s
time required, t = 2s
Force applied = -1500N ( here the negative sign indicates the force is applied in the opposite direction of the motion. Therefore it causes deceleration and makes the car come to rest.)
F = Change in momentum/ time
1. Change in momentum = Fx t = -3000 kg m/s
The negative sign tells us that the momentum has decreased.
2. Retardation,a = (v - u)/t = (0-30)/2 = -15m/s2
3. Mass of the car = F/a = (-1500)/(-15) = 100 kg.
The signs of F and a are important. Both the quantities can be negative as well as positive or zero.
Regards