Answer to Question #288386 in Physics for Junard

Question

A 3.5 kg rifle fires an 11g bullet with a velocity of 575 m/s. a.) What is the recoil velocity of the rifle. b.) If the shooter holds the rifle firmly against his shoulder,what will be the recoil velocity?

Assume the mass of shooter is 45kg

Answer 1

a) Find the recoil velocity:

$$0=mv+Mu→u=v\dfrac mM=1.81\text{ m/s}.$$

b) In this case:

$$0=mv+(M+M_s)u→v\dfrac{m}{M+M_s}=0.13\text{ m/s}.$$