Question

A projectile launcher has a mass of 3 kg. it fires a projectile of mass 0.08 kg horizontally at a speed of 300 m/s. a. what is the total momentum of the system before the projectile is fired? b. what is the total momentum of the system after the projectile is fired? c. what is the recoil velocity of the launcher?

Answer 1

a. The "system" is stationary; momentum p = 0.
c. 0 = 0.08kg 300m/s + 3kg v
v = -8 m/s (the negative sign indicates recoil)