Question

a car of mass 500 kg is moving with a velocity of 36kilo metre per hour when brakes applied it stop with uniform negative acceleration at a distance of 150 calculate the force applied by the brakes of the car and the workdone before stopping ???

Answer 1

m=500 kg
u=30kmph=10m/sec
v= 0
a = ?
s = 150 mtr
from,

v×v - u×u = 2as
0 - 100 = 300a
a= -100÷300
= - 0.33 m/sec^2
[-] indicates opposite direction
Force applied by brakes = m × a
=500 × 0.33
=165N

Work done = F×S
= 165×150=24750J

Answer 2

Given:
mass=m=500kg
u=36km/hrx5/18=10m/s
v=0 m/s
S=150m
V²-u²=2as
0-10x10=2a*150
a=-100/300=-0.33m/s²
Force=?
Force=F=m*a=500*(-0.33)=-165N
Therefore a forec of 165 N acts in opposite direction.
Workdone=Forcex displacement=165x150=24750J