Question

A bullet fired into a large block of wood of uniform resistance, hits the block with a velocity of $48m{s}^{-1}$. It penetrates a distance of 60 cm and the velocity is then reduced to $24m{s}^{-1}$. It then penetrates a further distance of (in cm)

• A. 50
• B. 16
• C. 18
• D. 20

Answer 1

The correct option is D 20

$u=48m{s}^{-1};$

$v=24m{s}^{-1};$

$s=\frac{60}{100}=0.6m$

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

$\frac{{24}^2-{48}^2}{2\times 0.6}=a$

$a=-1440m{s}^{-2}$

$u=24;$ $v=0;$

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

$=\frac{{24}^2}{2\times 1440}$

$=0.2m$

$=20cm$