A blue billiard ball with mass m crashes into a red billiard ball with the same mass that is at rest. The collision results in t
he blue billiard ball traveling with a velocity of v and the red billiard ball travelling with a velocity of 3v. In terms of v and m, determine the blue billiard ball’s velocity before the collision...
Draw a diagram to illustrate the problem as shown below. Each ball has mass = m. The initial velocity of the blue ball = u. The initial velocity of the red ball = 0.
Initial total momentum is P1 = m*u + m*0 = mu Final momentum is P2 = mv + 3mv = 4mv
Because momentum is conserved, mu = 4mv u = 4v
Answer: The velocity of the blue ball before the collision is 4v.