Question

A bullet of mass 20 grams moving with speed of 75 MS - 1 hits a fixed wooden plank and comes to rest after penetrating a distance of 5 centimetre what is the average resistive force exerted by the wooden plank on the bullet

Answer 1

By kinematic equation:
v^2=u^2+2as
0=75^2+2*a*0.05m
a*0.1=-5625
a=-56250
therefore,
resisting acceleration=56250m/s^2
Hence,
f=ma
f=0.02kg*56250m/s^2
average resistive force=1125N