A car is moving with a uniform velocity of 30 m s−1. It is stopped in 2 s by applying a force of 1500 N through its brakes. Calculate:
(a) the change in momentum of car,
(b) the retardation produced in car and
(c) the mass of the car.
Given:
Initial velocity = 30 m/s
Final velocity = 0 m/s
Time required, t = 2 s
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.)
(i) F =
Change in momentum = Fx t = -3000 kg m/s
The negative sign tells us that the momentum has decreased.
(ii) Acceleration, a =
Hence, the retardation is 15 m/s2.
Mass of the car == 100 kg