Question

A4.
is the force of the nail on the hammer?
A motorcar of mass 1200 kg is moving along a straight line
with a uniform velocity of 90 km/h. Its velocity is slowed down
to 18 km/h in 4 s by an unbalanced external force. Calculate
the acceleration and change in momentum. Also calculate the
magnitude of the force required.​

Answer 1

A motor car of mass 1200 kg is moving along a straight line with a uniform velocity of the 90 km/h. It's velocity is slowed down to 36 km/h in 4 second by an unbalanced force. Calculate the acceleration and change in the momentum. Also calculate the magnitude of force required.

m = 1200kg

u = 90*5/18 m/s = 25 m/s

v = 36 * 5/18 m/s = 10m/s

t = 4 s

Using :- v = u + at

10 = 25 + a * 4

a = -15/4 = 3.75 m/s

Motor car's Initial momentum :-

1200 * 25 = 30000 kg m/s

Motor car's Final momentum :-

1200 * 10 = 12000 kg m/s

Change in momentum :-

=(12000 - 30000)

= -18000 kg m/s

Force, F = 18000/4

= -4500 N