Question

A bullet fired in to a target loses half of its velocity after penetrating 25cm.how much further will it penetrate before coming to rest?

Answer 1

We know that

$v^2=u^2+2as$

$\frac{u^2}{4}=u^2+2a\times25\\-\frac{3u^2}{4}=50a\\a=-\frac{3}{200}u^2$

$u^2=v^2+2as$

Put a value

u=0

$0=u^2-2\times\frac{3}{200}u^2s\\s=\frac{100}{3}cm$