1. Momentum and Impulse Reactions to Collisions

2. Momentum Momentum: The vector quantity defined by the product of mass and velocity for a MOVING object. Equation: ρ = m * v Momentum = mass (kg) * velocity (m/s) All objects have INERTIA because of their mass, ONLY MOVING OBJECTS HAVE MOMENTUM!

3. IMPULSE All changes in an object’s momentum are caused by external forces. The rate of change in an object’s momentum has a proportional relationship to the force causing the change. The product of the two quantities is called IMPULSE, and is always equal to the change in the object’s momentum. Δρ = F* Δt Change in Momentum = Force * Time force is applied

4. Two Types of Collisions Elastic Collisions – Objects make contact but separate after contact. “BOUNCY” Inelastic Collision – Objects make contact and remain connected afterwards. “STICKY”

5. Conservation of Momentum The TOTAL MOMENTUM in a system of objects must remain the same unless objects are acted on by outside forces. The COMBINED MOMENTA of all the objects before the collision has to be equal to the combined momenta after the collision.

6. Conservation of Momentum for different collisions Elastic Collisions: ρ 1 before + ρ 2 before = ρ 1 after + ρ 2 after (m 1 *v 1 ) before + (m 2 *v 2 ) before = (m 1 *v 1 ) after + (m 2 *v 2 ) after Inelastic Collisions: ρ 1 before + ρ 2 before = ρ (1+2) after (m 1 *v 1 ) before + (m 2 *v 2 ) before = (m 1 + m 2 )*v 3after