Problem 1 A 0.5 kg billiards ball travelling to the right at 8 m/s (i.e. with initial positive pm momentum) collides with another billiards hall of the same mass which is initially at rest . The gure to the right shows the momentum vector of one ball after the collision. Which of the following best describes the momentum vector of the second hall after the collision? The initial momentumnf : 0.5 X 8:4kg *m/s) equals the final total momentum So the momentum vector of the second ball needs to cancel the y-component of momentum and add up to 4kg *m/s Answer: Vector points to (2,-2)