Question

a cricket ball of mass 150 gram is moving with a velocity of 12 metre per second and his hit by a bat so that the ball is turned back with a velocity of 20 m per second . the force of the blow acts for 0.01 second on the ball. find the average force exerted by the Bat and the ball

Answer 1

Weight of ball = 150g=150÷1000kg=0.15kg
initial velocity of ball=12m/sec(let's take it positive as the final velocity is in an opposite direction of initial velocity).
final velocity= -20m/sec(as it is on an opposite direction to initial velocity).
initial momentum- final momentum=
0.15kg×(-20)m/sec - 0.15kg×12m/sec=
3kg.m/s-1.8kg.m/s= 1.2kg.m/s
Now,as force is rate of change of momentum.so, 1.2kg.m/s÷0.01s=
1.2×10^-2 kg.m/sec^2 or
1.2×10^-2. N is the average force.