Question

A lead bullet of mass $20g$, travelling with a velocity of $350m{s}^{-1}$, comes to rest after penetrating $40cm$ in a still target. Find the retardation caused by it.

• A. $3.5\times {10}^{5}m{s}^{-2}$
• B. $1.53\times {10}^{3}m{s}^{-2}$
• C. $1.53\times {10}^{5}m{s}^{-2}$
• D. $1.53\times {10}^{1}m{s}^{-2}$

Answer 1

The correct option is C $1.53\times {10}^{5}m{s}^{-2}$

Given mass of the body as 20 g equal to 1/50 Kg.Here we have final velocity as 0 m/sec and initial velocity as 350 m/sec. Acceleration is nothing but rate of change of velocity.

$s=(v^2-u^2)/2a\Rightarrow$ $0.4={350}^2-0^2/2a\Rightarrow$ $a={350}^2/\mathrm{0.8.}$

$a=1.53\times {10}^{5}m/s^2$.