Question

A 5.5 kg rifle fires an 11 g bullet with a velocity of 1000 m/s. (a) What is the recoil velocity of the rifle? (b) If the shooter holds the rifle firmly against his shoulder, What will be the recoil velocity? Assume the mass of the shooter is 120 kg.
Please answer seriously (;´༎ຶٹ༎ຶ`)​

Answer 1

Given,

Mass of a rifle = 5.5 kg

Mass of a bullet = 11 g

Speed of a bullet = 1000 m/s

To find,

(a) The recoil velocity of the rifle.

(b) If the shooter holds the rifle firmly against his shoulder, What will be the recoil velocity.

Solution,

(a) Let v₁ is the recoil velocity of the rifle. We can use the conservation of momentum to find it. The momentum of the system will remains conserved.

$m_1v_1=m_2v_2\\\\v_1=\dfrac{m_2v_2}{m_1}\\\\v_1=\dfrac{0.011\times 1000}{5.5}\\\\v_1=2\ m/s$

So, the recoil velocity of the rifle is 2 m/s and it is in opposite direction of he bullet.

(b) Let V is the recoil velocity if the shooter holds the rifle firmly against his shoulder. Again using the conservation of momentum.

$V=\dfrac{0.011\times 1000}{120}\\\\v=0.091\ m/s$

Therefore, this is the required solution.