2. Impulse and Momentum Dr Ajay Kumar Professor School of Physical Education DAVV Indore

3. Momentum and Collisions This chapter is concerned with inertia and motion. Momentum helps us understand collisions. Elastic Collisions - objects rebound Inelastic Collisions - object stick together an usually become distorted and generate heat

4. Momentum Momentum = mass  velocity p = mv Momentum is a vector quantity.

5. A large truck has more momentum than a car moving at the same speed because it has a greater mass. Which is more difficult to slow down? The car or the large truck? Large Momentum Examples: –Huge ship moving at a small velocity –High velocity bullet

6. Impulse In order to change the momentum of an object you must apply a force over some time interval. Impulse = Force  time interval = F t

7. Impulse and Momentum Impulse = Change in Momentum F  t = mv f - mv i

8. Conservation of Momentum This means that the momentum doesn’t change. Recall that F t =  mv) In this equation, F is the "external force". Internal forces cannot cause a change in momentum.

9. Examples Conservation of Momentum: If there are no external forces, the total momentum for a system remains unchanged. Example 1: a person sitting inside a car pushing against the dashboard Example 2: a bullet fired from a rifle Example 3: a rocket in space m 1 u 1 + m 2 u 2 = m 1 v 1 - m 2 v 2

10. Coefficient of Restitution For perfectly elastic collisions e=1. If the two object stick together, e=0. Otherwise 0<e<1.