For an experiment in physics class, I had to roll a steel ball down a ramp so that it makes a collision with another steel ball of the same size, knocking it off a support near the edge of the table, and go off in different directions and land on a sheet, on the bottom of the table, which marks where the two balls landed. We are studing the momentum of this collision, but I am having trouble finding the initial momentum of the ball at rest before the collision and adding vectors. The procedures and questions for this experiment are as follows: 1. Draw a line joining X (the point of collision) with the point of contact of mass 1. Draw another line joining X with the point of contact of mass 2. The length of these two lines represents the final momentum vectors of mass 1 and mass 2. 2. Measure the angles between these momentum lines and draw a scale vector diagram to represent the sum of the two final momentum vectors. For addition of vectors, join them head to tail. Find the resultant momentum. P(total) = P(total)(after collision) m1v1 + m2v2 = m1v1(after) + m2v2(after) since masses are equal: v1 + v2 = v1 (after) + v2 (after) --> momentum is proportional to velocity, proportional to distance For v1, I rolled one of the balls down the ramp alone and got the distance it landed on the bottom of the table and said that the length of this line represented the initial momentum vector for mass 1. I am also guessing that the inital momentum for mass 2 is zero because it is at rest. I am completely stuck...is the sum of the distance the balls of mass 1 and 2 travel the total momentum after they collide?? If someone could tell me ANY useful information that I should know, that would be grrrrrrrreat.