Rifle weight 4 kg, bullet weight 0.05 kg, bullet speed 280 m / s find the speed of the rifle?

| May 30, 2021 | education

Rifle weight 4 kg, bullet weight 0.05 kg, bullet speed 280 m / s find the speed of the rifle? what is the speed of the rifle if the mass of a person is 70kg?

mw = 4 kg.

mp = 0.05 kg.

Vp = 280 m / s.

mh = 70 kg.

Vв -?

Vch -?

When a bullet is fired from a rifle, the law of conservation of momentum is valid: the impulse of the bullet mp * Vp is oppositely directed and equal to the impulse of the rifle mw * Vw: mp * Vp = mw * Vw.

Vw = mp * Vp / mw.

Vw = 0.05 kg * 280 m / s / 4 kg = 3.5 m / s.

When a person holds a rifle in his hands, then the law of conservation of momentum will take the form: mp * Vp = (mv + mh) * Vh.

Vch = mp * Vp / (mv + mh).

Vch = 0.05 kg * 280 m / s / (4 kg + 70 kg) = 0.2 m / s.

Answer: after the shot, the speed of the rifle will be Vw = 3.5 m / s, the speed of a person with a rifle is Vc = 0.2 m / s.



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