Question

A bullet of mass $20$ $g$ is moving with a speed of $150$ $m{s}^{-1}$. It strikes a target and is brought to rest after piercing $10$ $cm$ into it. Calculate the average force of resistance offered by the target.

• A. $2500$ $N$
• B. $2000$ $J$
• C. $2250$ $N$
• D. $2100$ $J$

Answer 1

The correct option is C $2250$ $N$

Mass $=20$ $g=0.02$ $kg$

Initial velocity $\left(u\right)=150$ $m{s}^{-1}$

Final velocity $\left(v\right)=0$ $m{s}^{-1}$

Distance travelled before coming to rest $\left(s\right)=10$ $cm=0.1$ $m$

$v^2=u^2-2as$

$\Rightarrow 0=(150{)}^2-2\cdot a\cdot 0.1=112500$ $m{s}^{-2}$

$f=ma$

$\Rightarrow f=0.02\times 112500$ $=2250$ $N$