Question

A bullet of mass $250\, g$ moving with a velocity $200\, m / s$ is stopped within $5\, cm$ of the target. The average resistance offered by the target is :

• A. 40 kN
• B. 30 kN
• C. 20 kN
• D. 10 kN

Answer 1

Answer: (D)

Average resistance offered by the target to the bullet is given by Newton's second law.
From equation of motion we have
$v^{2}=u^{2}-2 a s$
where, $v$ is final velocity, $u$ is initial velocity, $a$ is acceleration and $s$ is displacement
Given, $u=200\, m / s,\, s=0.05\, m,\, v=0$
$\therefore O=(200)^{2}-2 a \times 0.05$
$\Rightarrow a=\frac{(200)^{2}}{2 \times 0.5}=4 \times 10^{4} m / s ^{2}$
Resistance offered $=F=m a$
$=0.25 \times 4 \times 10^{4}$
$=10 \times 10^{3} N =10\, kN$