A miniature spring-loaded, radio-controlled gun is mounted on an air puck. The gun's bullet has a mass of 5.00 g, and the gun and puck have a combined mass of 120 g. With the system initially at rest, the radio controlled trigger releases the bullet causing the puck and empty gun to move with a speed of 0.500 m/s. What is the bullet's speed?

Answer 1

momentum is conserved

the momentum of the bullet is equal to the momentum of the puck/gun
... but in the opposite direction

(mass bullet) * (speed bullet) = (mass puck/gun) * (speed puck/gun)

Answer 2

12 J