Question

A scooter is moving with a velocity of 25 m/s and it takes 5 sec to stop after the brakes are applied. If the mass of the scooter along with the rider is 180 kg, find the change in momentum.

CBSE Class IX Science SA 2 (3 Marks)

Answer 1

u = 25m/s, v = 0, t = 5 s, m = 180 kg

pi = mu = 180 x 25
       4500 kg m / s
pf = my
    = 180 x 0
    = 0 kgm /s
pf - pi = 0 - 4500
          = -4500 kg m / s

Hence, the change in momentum is -4500 kg m/s.

Answer 2

initial momentum P =m × u

=180×25=4500kgm/s

final momentum =m × v

180×0(v=0,as brakes are applied)

0kgm/s

Change in momentum=4500-0=4500kgm/s

Therefore Change in Momentum= 4500kgm/s