posted by Kushagra .
During a football match, the ball shot towards the goal struck the defender's foot at the speed of 10m/s and it bounced back at 20m/s. If the time of impact was 0.2 sec, and mass of the ball 0.5 kg,then find the average force exerted by defender on the ball.
a = Vf-Vo)/t,
a = (--20-10) / 0.2 = -150 m/s^2 in
F = ma = 0.5 * (-150) = -75 N. = opposing force.