Question

A bullet of mass 20 g travelling horizontally with a
velocity of 200 ms-7 strikes a stationary wooden
block and comes to rest in 0.01 s with uniform
retardation. The total distance of penetration of
bullet into the block is
(1)0.5 m
(2) 1 m
(3) 0.8 m
(4) 0.25 m​

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