a motorcar is moving with a velocity of 108 km / h and it takes 4s to stop after the brakes are applied calculate the force exerted by the brakes on the motorcar if it's mass along with the passengers is 1000 kg

Answer: - 7500N

Explanation:

Given the following:

Initial Velocity of car = 108km/hr

Time taken to stop after applying brakes = 4s

Mass of passengers in car = 1000kg

Force exerted by the brakes on the car = ?

After 4s, then final Velocity (V) = 0

Initial Velocity (u) of the car = 108km/hr

108km/hr = (108 * 1000) m : (3600) s = 30m/s

Force exerted = mass (m) * acceleration (a)

Acceleration of car = Change in Velocity with time

a = (v - u) / t

a = (0 - 30) / 4

a = - 30 / 4

a = - 7.5m/s^2

Therefore,

Force exerted = mass (m) * acceleration (a)

Force exerted = 1000kg * (-7.5) m/s^2

Force exerted = - 7500N