Question

A $30$ gm bullet initially travelling at $120$ m/s penetrates $12$ cm into a wooden block. The average resistance exerted by the wooden block is?

• A. $2850$ N
• B. $2200$ N
• C. $2000$ N
• D. $1800$ N

Answer 1

The correct option is D $1800$ N

$u=120m/s$ and $v=0$

$s=12cm=0.12m$ and $m=30g=0.03kg$

$a=\frac{v^2-u^2}{2s}=\frac{0-{120}^2}{2\times 0.12}=-60000m/s^2$

Force $F=ma=0.03\times 60000=-1800N$

(-ve sign shows that force is resistive in nature)

Answer-(D)