Question

A car of mass 5000 kg is moving with velocity 20 m/s when, unbalanced force is applied on the car for 3 sec. Its velocity becomes 17 m/s. Calculate retardation, change in momentum, rate of change of momentum.

Answer 1

-a=17-20÷3=-1

change in momentum=5000 (17)-5000 (20)=

Answer 2

m=5000 kg
u=20 m/s
t=3 sec
v=17 m/s

a=(v-u)/t
=(17-20)/17
=-3/3
= -1 m/s square
retardation= 1 m/s square

initial momentum= mu
=5000×20 kg m/s
=100000 kg m/s

final momentum= mv
=5000× 17 kgm/s
85000 kg m/ s

rate of change in momentum
=mv - mu
= 85000-100000
= -15000 kg m/s

I m not sure if this is right