Introduction Momentum is inertia in motion. It is a measurement of an object's resistance to change in motion. Momentum is directly proportional to the object's mass and its velocity. Momentum. p, can be calculated using the following expression: p = mv. where m is the mass of the object and v is the object's velocity. When dealing with collisions it is often convenient to describe the situation in terms of momentum conservation. If there is no net external force acting on a system. the momentum of the system will be conserved. Stated in another form. if there is no net external influence on a system the initial momentum, pi. of a system will equal the final momentum, pf. of the system. Written in equation format: pi = p,. In today's activity we are going to test the idea of conservation of momentum through collisions. Instead of using carts and motion detectors to run the experiment, you will be the objects colliding! Shown in the figure below is a sketch of two students' (on rollerblades) motion before and after a collision. Before Collision '- x i A 0 o s. I dF After Collision IRIS mm 00 \\lg/ Activity 1. The collisions we will be performing today will go as follows: a. roller A will roll toward roller B, who is initially at rest; b. rollers A and B will collide; and c. the two rollers will grab each other's arms and move together after the collision. What type of collision is this and how do you know? 2. Practice this collision a couple of times to make sure that your distances are appropriate and that all parties understand their role