Question

Bullet moving with speed 150m/s penetrates 3.5 cm into a tree, then stops. Find magnitude of retardation and time taken to stop after striking.

Answer 1

Hii dear

# Given-

u=150m/s

v=0m/s

s=3.5cm=3.5×10^-2m

# Solution-

By 3rd kinematic eqn,

v^2 = u^2 + 2as

0^2 = 150^2 + 2×3.5×10^-2×a

a = -3.2×10^5m/s^2

By 1st kinematic eqn,

v = u + at

t = (v-u)/a

t = (0-150)/(-3.2×10^5)

t = 4.69×10^-4 s

Hence, bullet will have retardation of -3.2×10^5 m/s^2 and will take 4.7×10^-4 s to penetrate.

Hope this helps you.