Question

A bullet travelling a velocity of 16$\frac{m}{s}$ penetrates a tree trunk and comes to rest in 0.4 m. Find the time taken during the retardation.

Answer 1

u = 16$\frac{m}{s}$ (intial), v = 0, S = 0.4 m

Deceleration, a = $\frac{v^2-u^2}{2S}$
= $\frac{0-{16}^2}{2\times 0.4}$
=320 $\frac{m}{s^2}$
time = $\frac{v-u}{a}$
= $\frac{0-16}{-320}$
=0.25 sec