Question

a motor car is moving with a velocity of 108 km per hour and it takes 4 seconds to stop after the brakes are applied calculate the force exerted by the brakes on the motor car if its mass along with the passengers is 1000 kg

Answer 1

Given ,

u = 108 km/h = 30 m/s , v = 0 m/s

t = 4 seconds and let deceleration be a, then

v = u+at

0 = 30+a(4)

a = -15/2 m/s²

We know that ,

F = ma = 1000(-15/2) = -7500 N

Answer 2

Answer:

-7500 N

Explanation:

u= 108 km/h=30 m/s

t= 4 s

v= 0 m/s

m= 1000 kg

F=ma

F=m×v-u/t

F=1000×0-30/4

=1000×(-7.5)

F= -7500 N