A bullet of mass 100g moving with20m/sec .Strikes a wooden plank and peretrates up to 20cm.Calculate the resistance offered by the wooden plank.

Answer 1

momentum = 0.100 * 20 = 2 kg m/s

distance into plank = .020 meter
average speed in plank = 20/2 = 10 m/s
time in plank = .020/10 = .002 s

average force = change in momentum/time
= 2/.002 = 1000 Newtons