Question

A tennis ball of mass 0.11 kg traveling at 40 m/s hits a wall head on and bounces off, returning along the same path at 30 m/s. (i) Calculate the change in velocity of the ball (ii) Calculate the change in momentum of that ball. including the unit in your answer.

Answer 1

1) change in v = 30-40
v=10m/s
2)p=m(v-u)

p= mv-mu
p=(0.11*-30)-(0.11*40)
p=-7.7 m/s(direction is upwards)

here v=-30 ,becoz it is bounced back

Answer 2

Answer:

i. change in velocity=-30-40

= - 70m/sec

ii. change in momentum=p2 -p1

=mu - mv

=0.11×(-30)-0.11×40

=0.11×(-70)

=-7.7kg-m/sec