A 2 kg ball of putty moving to the right at 3m/s has a head-on inelastic collision with a 1 kg ball of putty moving to the left at 3m/s. What is the final magnitude and direction of the velocity of the stuck together balls after the collision?

Answer 1

Linear momentum is conserved. Therefore
M1*V1 + M2*V2 = (M1 + M2)*Vfinal

2*3 -1*3 = (2 + 1)*Vfinal
Vfinal = 1 m/s
in the positive (right) direction