1. Welcome back! Please pick up your schedule from the table by the door.

2. Expectations Phones will be collected if they are seen. Cheating will not be tolerated. 1.Working with a classmate is fine 2.Copying another students work will earn you a zero on the assignment. When I ask for your attention please stop talking and face the front of the class.

3. Expectations Remain in your seats until the bell rings. Anyone out of their seats before the bell rings will be asked to stay after class. If you are absent please see me the day you return for any assignments you missed. Late work will earn a 10 point deduction for each day it is late Late work can only be turned in up to three days late for credit.

4. Momentum

5. Momentum: Physics term Momentum is a physics term that means the amount of motion in a moving body. The MORE momentum an object has the GREATER the force must be applied to stop it & vice versa The lesser the momentum the less force must be applied to stop the object.

6. Momentum Equation Momentum can be represented in an equation p=mv (use small p, large P stands for pressure!) p is momentum m is mass v is velocity Momentum is a vector because it has a magnitude and a direction

7. So an object’s momentum depends on how big the object is and how fast it is traveling.

8. Momentum Problems Momentum (p) = Mass (m) x Velocity (v) The resulting units for momentum are: kilogrammeters/second or kgm/sec Sample problem: Calculate the momentum for a 60 kg student running through the halls at a velocity of 4 m/sec. Include the correct units ! p = mv p = 60 kg 4 m/sec p = 240 kg m/sec

9. Momentum Practice p = mv A deer with a mass of 146 kg is running head on toward you with a speed of 17 m/s. The deer is running south. Find the momentum of the deer. W: T: F: mass = 146 kg; velocity = 17 m/s momentum (p) p = mv = 146 kg x 17 m/s Answer: 2482 kg-m/s to South (2.5 x 10 3 kg-m/s, South)

10. Momentum Practice p = mv What velocity must a 1210 kg car have in order to have the same momentum as the deer in the previous problem? W: T: F: mass = 1210 kg; momentum = 2482 kg-m/s South velocity (v) p = mv => manipulate formula => v = p/m v = 2482 kg-m/s ÷ 1210 kg Answer: 2.05 m/s, South

11. Momentum Practice p (total) = p (1) + p (2) + p (n…..) A 21 kg child on a 5.9 kg bike is riding with a velocity of 4.5 m/s to the northwest. What is the total momentum of the child & the bike? W: T: F: mass (child) =21 kg; mass (bike) =5.9 kg; velocity=4.5 m/s p (total) p = m (total) x v => (21 kg + 5.9 kg) x 4.5 m/s Answer: 121.05 kg-m/s northwest How would you calculate the total momentum if you had 2 objects with 2 different velocities?

12. Impulse Impulse is a change of momentum in an object. When you apply a force on an object, you also exert an impulse on it. When something exerts a force on you, it also exerts an impulse on you. Forces and impulses always go together. Impulse, like force, is a vector.

13. Impulse Equation A force must act on an object for a time in order to change its velocity. Impulse is equal to force multiplied by time. J=Ft J=Impulse F=force t=time The units for impulse is Newton Seconds or Ns

14. Impulse and velocity You can get the same impulse by applying a large force for a short time, or applying a small force for a long time.

15. Impulse and Momentum An impulse will cause a change in momentum. J = Δp Or Ft = p 2 - p 1 = m 2 v 2 – m 1 v 1