1. Momentum pg. 27

2. Objectives Calculate the momentum of an object. Identify the units of momentum. Calculate the momentum of a physical system consisting of multiple objects moving in different directions. Momentum Impulse Terms

3. What is momentum? Momentum is mass in motion. This means an object has to have 2 things in order to have momentum: 1  Mass 2  Velocity (has to be moving) You might have heard the word momentum before just not in a physics sense. Can you think of any examples of when the word momentum is used outside of class?

4. The momentum of an object is its mass multiplied by its velocity. Momentum is a vector. - What does vector mean again? Equations  Momentum Rearrange the formula above to solve for: Mass:Velocity: It can be positive (+) or negative (-)

5. Units of momentum Momentum has units of mass multiplied by velocity. mass in velocity in Units for momentum  by kg m/s

6. Momentum p = 100 kg m/s What about these two spheres, do they have the same or different momentum? Same

7. Momentum This means that the velocity is responsible for determining the sign of an object’s momentum Think about the equation for momentum. If an object has a negative momentum, what does that mean HAS to be negative?

8. Lets test your knowledge A red truck and a blue truck have the same mass. The red truck is parked, and the blue truck is traveling along the highway at 60 mph. a)Do both trucks have inertia? a)Do both trucks have momentum? Yes because they both have mass No. The blue truck has momentum. The red truck has NO momentum because its not moving.

9. Engaging with the concepts Momentum 7.0 60 1. What is the momentum of a 60 kg sprinter running at 7.0 m/s? 2. What is the velocity of the sprinter if her momentum is 270 kg m/s? 3. If she wanted to double her momentum, how fast would she have to run?

10. Engaging with the concepts 4. A 2,000 kg car and a 4,000 kg truck are both traveling at 10 m/s when they hit a wall. 4a. Which has more momentum before impact? 4b. How much more inertia does the truck have than the car? 5. A boulder is dropped from rest and hits the ground at a speed of 15 m/s, transferring 1,200 kg m/s of momentum to the Earth. What is its mass?

11. Engaging with the concepts Velocity 1001.0 6a. Create two objects with a momentum of 100 kg m/s, but with masses of 1.0 kg and 4.0 kg. 6b. If the mass is four times greater, how does the velocity change?

12. Consider these two objects A.The 100 kg sphere B.The 1 kg sphere C.It’s a tie. D.More information is needed. If the same stopping force is applied to each, which sphere will stop first?

13. Consider these two objects A.The 100 kg sphere B.The 1 kg sphere C.It’s a tie. D.More information is needed. If the same stopping force is applied to each, which sphere will stop first? Why?

14. Momentum of a system (we’ll talk more about this later) p = -100 kg m/s p = +100 kg m/s A. Zero B.+100 kg m/s A.+200 kg m/s What is the TOTAL momentum of this system of two balls?

15. Momentum of a system p = -100 kg m/s p = +100 kg m/s A. Zero B.+100 kg m/s A.+200 kg m/s What is the total momentum of this system of two balls? 100 kg m/s + -100kg m/s = 0 kg m/s

16. Homework 1.Calculate the momentum of a 1.0 kg object moving with a velocity of +20 m/s. 2.What is the velocity of an object that has a momentum of -30 kg m/s and a mass of 3.0 kilograms? 3.Two objects have equal momentum but one has four times the mass of the other. What is the relationship between their velocities?

17. Homework 4.Which answer below shows the correct units for momentum? A.kg m/s 2 B.kg m 2 /s 2 C.kg m/s D.kg s/m

18. Homework 5. Two bowling balls each have a mass of 4.0 kg. The red ball is moving east at 2.0 m/s. The blue ball is moving west at 1.0 m/s. Calculate the total momentum of the system.