Question

A ball of mass 1 kg travelling horizontally with a velocity of 15 m/s strikes and enters a
stationary bag of sand and comes to rest in 0.3 s. Calculate the distance of penetration of the
ball in the sand. Also calculate the magnitude of the force exerted by the sand on the ball.

Answer 1

Explanation:

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)

v

2

=u

2

+2as

0=150

2

+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