Question

A gun fires a bullet of mass 5g moving with a velocity 1000 m/s. if the average force

Answer 1

Finding this answer relies on the principle of conservation of momentum which arises from conservation of energy. They basically say that the net energy or momentum of a system remains constant. Also remember to convert the bullet’s mass to kilograms. (10g = .01kg)

Let's solve with momentum: (P is momentum, the rifle has mass M and velocity V while the bullet has mass m and velocity v)

P (initial)=P (final) = 0

P (bullet) = P (rifle)

mv = MV

V = mv/M

So, recoil velocity = (0.01 * 400)/4 = 1 m/s