Question

The velocity of a bullet is reduced from $100m/s$ to $0m/s$ while travelling through a wooden block of thickness $10cm$. The retardation, assuming it to be uniform will be:

• A. $5\times {10}^{4}m/s^2$
• B. $12\times {10}^{4}m/s^2$
• C. $14\times {10}^{4}m/s^2$
• D. $1\times {10}^{4}m/s^2$

Answer 1

The correct option is A $5\times {10}^{4}m/s^2$

$v^2=u^2+2as$
$\text{Substituting}v=0,u=100m/s,s=10cm=0.1m$
$a=-\frac{{100}^2}{0.1\times 2}$
$a=-5\times {10}^{4}m/s^2$