Question

a football of mass 0.38 kg is traveling towards a boy at 2.8ms-1. the boy kicks the ball with a force of 21N, reversing its direction. if the time of imapct between the football and boy’s foot is 250ms. what is the new speed of trhe ball?

Answer 1

Answer:

Final speed in reverse direction will be 11 m/s

Explanation:

As per impulse momentum theorem we know that

Change in momentum of the object is product of force and time

so we have

$P_f - P_i = F\Delta t$

now we have

$P_f = mv_f$

$P_i = mv_i$

$\Delta t = 250 ms$

F = 21 N

now we have

$0.38(v_f) - 0.38(-2.8) = 21(250\times 10^{-3})$

$v_f = 13.82 - 2.8$

$v_f = 11 m/s$