Question

A bullet of mass $20$g is fired from a rifle of $8$kg with an initial velocity of $100m$ $s^{-1}$. Find the final velocity of the recoil of the rifle.

• A. $-0.25m{s}^{-1}$
• B. $2.5m{s}^{-1}$
• C. $25m{s}^{-1}$
• D. $250m{s}^{-1}$

Answer 1

The correct option is A $-0.25m{s}^{-1}$

Since linear momentum is conserved

$\frac{20}{1000}\times 100+8\times V_2=0$

$\Rightarrow V_2=\frac{-2}{8}=-0.25m/s$