Find the recoil speed of the rifle.?

Question

A rifle with a weight of 20 N fires a 4.5 g bullet with a speed of 210 m/s.
(a) Find the recoil speed of the rifle.
(b) If a 775 N man holds the rifle firmly against his shoulder, find the recoil speed of the man and rifle.

Answer 1

Conservation of momentum
Momentum before firing equal momentum after firing.
m1U1+m2U2 = m1V1+m2V2
Before firing speed of the gun U1=0 and th espeed of the bullet U2=0. Then we have
0=m1V1+m2V2

a) So
m1V1=-m2V2
V1=-(m2/m1)V2 (just keep in mind that m1=W1/g)
V1= -(gm2/W1)V2

b)
V1=-(gm2((W1+W2))V2

Answer 2

Physics is the form you calculate real international activities, no longer inevitably the way it works. besides, a splash i'm going to furnish is that an identical volume of stress or potential that propels the bullet from the gun additionally propels the heavy rifle the alternative course. So the base line is to apply one in each of your uncomplicated physics equations, and the linked fee and weight of the bullet, to locate the stress. Then use this stress and the load of the rifle to locate the linked fee of the rifle. desire this helps. EDIT got here across it, you like the equation for impulse. impulse=mass x velocity, on your difficulty impulse=.00484kg x 516m/s you get impulse = 2.479 kg-m/s now use this impusle and the plenty heavier mass of the rifle to locate the linked fee of the rifle.