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 resistive force offered by the target.

• A. $30.625N$
• B. $3062.5N$
• C. $306.25N$
• D. $3.0625N$

Answer 1

The correct option is B $3062.5N$

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.

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

$F=m\times a,$
$F=\left(1/50\right)\times {350}^2/0.8=3062.5N.$