Answer to Question #152731 in Classical Mechanics for GuardianVex

Question

What do you mean by recoil of gun? Obtain an expression for recoil velocity? A shell of mass 30g is fired from a gun, with a speed of 80m/s. Calculate the recoil velocity of gun if its mass is 200g.

Answer 1

$\text{A recoil is a movement backwards, usually from some force or impact. }$

$\text{We use the law of conservation of momentum:}$

$m_g*V_g+m_b*V_b= const$

$\text{where:}$

$m_g,V_g-\text{gun mass and speed}$

$m_b,V_b-\text{bullet mass and speed}$

$const = 0 \text{ since before the start of the movement the speed of the gun }$

$\text{and the bullet are 0}$

$m_g*V_g+m_b*V_b= 0$

$V_g= -\frac{m_b*V_b}{m_g}$

$V_g\text{ has a minus sign because it is opposite to the direction of the bullet}$

$|V_g|= \frac{0.03*80}{0.2}=12m/s$

Answer:12m/s gun speed