Question

A bullet on penetrating $30cm$ into its target loses its velocity by $50\%$. What additional distance will it penetrate into the target before it comes to rest?

• A. $30cm$
• B. $20cm$
• C. $10cm$
• D. $5cm$

Answer 1

The correct option is C

$10cm$

Step 1: Given data

Distance, $s=30cm$

Initial velocity $=u$

Final velocity $=v$

Step 2: Find distance covered before rest

From $3^{rd}$ law of motion

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

Stage 1: Velocity become half

$(u^2/4)=u^2+2ax30x{10}^{-2}$

Steg 2: Final velocity became zero

$0=(u^2/4)+2ax$

Solving for both cases, we get

$x=10cm$

Hence, option C is correct.