Question

A bullet of mass $0.04$ moving with a speed of $90{ms}^{-1}$ enters a heavy wooden block and is stopped after a distance of $60cm$. The average resistance force exerted by the block on the bullet is

• A. $180N$
• B. $220N$
• C. $270N$
• D. $320N$

Answer 1

Answer: (C)

$270N$

Given,

$m=0.04kg$

$u=90m/s$

$v=0m/s$

$s=60cm=0.60m$

From 3rd equation of motion,

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

$a=\frac{v^2-u^2}{2s}$

$a=\frac{(0{)}^2-(90{)}^2}{2\times 0.60}$

$a=-6750m/s^2$

The average resistance force exerted by the block on the bullet is

$F=ma$

$F=0.04\times \left(6750\right)$

$F=270N$

The correct option is C.