Question

A bullet of mass 3 kg is fired at a speed of 108 km/hr towards a block of mass 12 kg placed on the ground. It was observed that the bullet penetrates into the block & comes out at a speed of 15 m/s. Find the speed acquired by the block.

• A. 3.75 m/s
• B. 5.25 m/s
• C. 4.25 m/s
• D. 2.25 m/s

Answer 1

The correct option is A 3.75 m/s

Applying conservation of momentum
$p_i=p_f$
$3\times (108\times \frac{5}{18})=3\times 15+12\times v$
3 $\times$ 30 = 45 + 12$v$
12$v$= 45
$\Rightarrow$$v$= 3.75 m/s