Question

A rifle with a mass of m1 = 3.4 kg fires a bullet with a mass of 7.7 g (0.0077 kg). The bullet moves with a velocity of 860 m/s after the rifle is fired. If external forces acting on the rifle can be ignored, what is the magnitude of the recoil velocity of the rifle?

Answer 1

Answer:

The magnitude of the recoil is v = 1.95 m/s

Explanation:

The momentum of bullet

P = m*v

P = 0.0077kg x 860m/s

P =  6.622 kg m/s

Now using the law of conservation of momentum we have,

P1 + P2 = 0

Now solve to V2 to find the velocity of the rifle so:

m1*v1 + m2*v2 = 0

3.4kg*v1 + 6.622 kg m/s = 0

3.4 kg*v1= -6.622 kg m/s

v1 = 6.622/3.4

v1 = 1.95 m/s