1. Momentum is what Newton called the “quantity of motion” of an object. Momentum

2. So What’s Momentum ? Momentum is the measure of mass in motion Momentum = mass x velocity This can be abbreviated to :. momentum = mv Or, if direction is not an important factor :.. momentum = mass x speed So, a really slow moving truck and an extremely fast roller skate can have the same momentum.

3. Question : Under what circumstances would the roller skate and the truck have the same momentum? If the roller skate moves really fast and the truck moves really slow, then they could have the same momentum. This is due to the fact that momentum is the mass of an object times the velocity it is travelling. A 1000 kg truck moving at 0.01 m/s has the same momentum as a 1 kg skate moving at 10 m/s. Both have a momentum of 10 kg m/s. (1000kg x.01m/s = 1kg x 10m/s = 10 kg x m/s ) 1000 kg1 kg.01 m/sec10 m/sec

4. ELASTIC COLLISIONS – objects bounce away INELASTIC COLLISIONS – objects stick together Momentum transfers from one object to another as they bounce off each other

5. Collisions on an air track Momentum Interactive

6. Copy the data table above into your notebook Predict: When two objects collide, what will happen to their motion? Momentum Table Mass - A (kg) V i of 1 m/s Collides with Mass – B (kg) V i of 0 m/s PredictionObserved Result 1.0 kg  0.7 kg 1.0 kg   1.4 kg Momentum Interactive

7. Conservation of Momentum Momentum = mass x velocity p = mv Momentum is conserved (total amount stays the same) if there are no outside forces when objects collide. Outside forces, like friction, take away from the total velocity. This takes away from the total momentum. The only forces present during the collision are the action-reaction force pairs. Collisions are not the only events in which momentum is conserved. In fact, momentum is conserved whenever the only forces acting on the objects are action-reaction force pairs. Conservation of momentum is really just another way to look at Newton’s Third Law.