Question

Calculate the recoil speed of a 1.4 kg rifle shooting 0.006 kg bullets with muzzle speed of 800 m/a.3.43 m/s

b.1.22 m/s
c.6.42 m/s
d.571 m/s

Answer 1

a) 3.43 m/s

Step-by-step explanation:

Due to the law of conservation of momentum, the total momentum of the bullet - rifle system must be conserved.

The total momentum before the bullet is shot is zero, because they are both at rest, so:

`p_i = 0`

Instead the total momentum of the system after the shot is:

`p_f = mv+MV`

where:

m = 0.006 kg is the mass of the bullet

M = 1.4 kg is the mass of the rifle

v = 800 m/s is the velocity of the bullet

V is the recoil velocity of the rifle

The total momentum is conserved, therefore we can write:

`p_i = p_f`

Which means:

`0=mv+MV`

Solving for V, we can find the recoil velocity of the rifle:

`V=-(mv)/(M)=-((0.006)(800))/(1.4)=-3.43 m/s`

where the negative sign indicates that the velocity is opposite to direction of the bullet: so the recoil speed is

a) 3.43 m/s