Question

A gun weighing 4 kg fires a bullet of 40 g with a velocity of $500m{s}^{-}1$. With what velocity does the gun recoil?

• A. $5m{s}^{-}1$
• B. $10m{s}^{-}1$
• C. $20m{s}^{-}1$
• D. $4m{s}^{-}1$

Answer 1

The correct option is A

$5m{s}^{-}1$

Mass of gun $m_1$= 4 kg,
Mass of bullet $m_2$ = 40 g = 0.04 kg
Let velocity of bullet be $v_2$
$V_2$ = $500m{s}^{-}1$
Using conservation of momentum : m1v1 = m2v2
Recoil velocity $v_1=\frac{m_2{v}_2}{m_1}$
$=\frac{0.04\times 500}{4}=5\frac{m}{s}$