1. Momentum & Collisions Physics - Chapter 6

2. Momentum  Vector quantity  Product of an objects mass and velocity  Represented by p  SI units of kg x m/s  Momentum is what makes it hard to stop an object rolling down a hill  P = m x v

3. A 2250 kg pickup truck has a velocity of 25 m/s to the east. What is the momentum of the truck?

4. Changes in momentum  A force applied for a certain time will cause a change in momentum  Impulse-momentum theorem FΔt = Δp or FΔt = Δp = mv f - mv i

5. A 1400 kg car moving westward with a velocity of 15 m/s collides with a utility pole and is brought to rest in 0.30 s. Find the force exerted on the car during the collision.

6. A 2240 kg car traveling to the west slows down uniformly from 20.0 m/s to 5.00 m/s. How long does it take the car to decelerate if the force on the car is 8410 N to the east?

7. Law of Conservation of Momentum  The total momentum of all objects interacting with one another remains constant.  In equation form: m 1 v 1,i +m 2 v 2,i = m 1 v 1,f +m 2 v 2,f total initial momentum = total final momentum

8. A 76 kg boater, initially at rest in a stationary 45 kg boat, steps out of the boat and onto the dock. IF the boater moves out of the boat with a velocity of 2.5 m/s to the right, what is the final velocity of the boat?

9. Perfectly Inelastic Collisions  A collision in which two objects stick together and move with a common velocity after colliding  Equation for a perfectly inelastic collision m 1 v 1 +m 2 v 2 =(m 1 +m 2 )v f  Be careful with signs for velocity!  Kinetic energy is not conserved

10. Elastic Collisions  A collision in which the total momentum and the total kinetic energy remain constant  After the collision, the two objects move separately

11. In real life…  Only particle collisions are truly considered elastic, however, some collisions are close enough to be approximated as elastic  Most collisions are somewhere between being elastic and perfectly inelastic

12. A 1850 kg luxury sedan stopped at a traffic light is struck from the rear by a compact car with a mass of 975 kg. The two cars become entangled as a result of the collision. If the compact car was moving at a velocity of 22.0 m/s to the north before the collision, what is the velocity of the entangled mass after the collision?

13. A 0.015 kg marble moving to the right at 0.225 m/s makes an elastic head-on collision with a 0.030 kg shooter marble moving to the left at 0.180 m/s. After the collision, the smaller marble moves to the left at 0.315 m/s. Neglect friction. What is the velocity of the 0.030 kg marble after the collision?