Question

a motor car is moving with a velocity of 108 km/h and it takes 4s stop after the brakes are applied. find the force exerted by the brakes on the motor car it if it's mass along with the passenger is 1000 kg

Answer 1

given
u=108km/h =108×5/18 =30m/sec
v=0 (brakes applied)
t=4s
so first :a=v-u/t
0-30/4
-30/4 = -7.5m/sec^2
then second;:F=m×a
F=1000×-7.5=-7500N

Answer 2

hey ur ans is..
u= 108km = 30m/s
v=0m/s
t=4sec
mass =1000kg
F= m(v-u/t)
= 1000*(0-30/4)
=1000*(-30/4)
=500*-15
= -7500N