Two balls are approaching each other head-on. Their velocities are +10.00 and -12.8 m/s.

(a) Determine the velocity of the center of mass of the two balls if they have the same mass.
m/s
(b) Determine the velocity of the center of mass of the two balls if the mass of one ball (v = 10.00 m/s) is twice the mass of the other ball (v = -12.8 m/s).
m/s

a) If they have the same mass, the center of mass velocity is the average velocity

b) Use the mass-weighted average
[2*10 + 1*(-12.8)]/3