Question

A bullet fired into a fixed target loses half its velocity after penetrating $3 \, cm$ . How much further it will penetrate before coming to rest assuming that it faces constant resistance to motion?

• A. $1.5cm$
• B. $1.0 \, cm$
• C. $3.0 \, cm$
• D. $2.0 \, cm$

Answer 1

Answer: (B)

For first part of penetration, by equation of motion,
$\left(\frac{u}{2}=(u-2 f(3)\right.$
or $3 u^{2}=24 f$
For latter part of penetration,
$0=\left(\frac{u}{2}\right)^{2}-2 f x$
or $u^{2}=8 f x$
Therefore,
$3 \times(8 f x)=24 f$
or $x=1 cm$