Question

A gun fires a bullet of mass 50g. The bullet of mass ‘m’ moving with a velocity of 500 m/s strikes a wooden plank and comes to rest in 0.05 s. Calculate (i) the retarding force experienced by the bullet (ii) the distance of penetration of the bullet in the wooden plank.

Answer 1

Answer:

Initial velocity of the bullet, u=150  ms−1

Final velocity of the bullet, v=0

Mass of the bullet, m=10 g=0.01 kg

Time taken by the bullet to come to rest, t=0.03 s

Let distance of penetration be s

v=u+at

0=150+a(0.03)  

⟹a=−5000 ms−2    (- sign shows retardation)

v2=u2+2as

0=1502+2×(−5000)×s

s=2.25 m

Magnitude of the force exerted by the wooden block, ∣F∣=m∣a∣

∣F∣=0.01×5000=50 N