DAY 47

#Goals: SWBAT...

1. Define "impulse"

2. Understand that a longer time period (larger delta t) results in a smaller force

3. Use the impulse-momentum equation to solve momentum problems.

Warm-Up (4min):

• https://www.youtube.com/watch?v=fdeH6Ksedwk
• Recall from your HW video: Impulse is the change in momentum (Δp).

1. Is the impulse when the brick hits the table the same or different as the brick hitting the foam?
2. When our video presenter jumps from the table, he begins falling. Does his momentum increase, remain constant, or decrease?
3. Does he want to experience a strong force when he lands? Why/why not?
4. How does he protect himself upon landing?
5. Why are running shoes helpful for our feet?

CLASSWORK

1. #047A: The connection between Impulse and Momentum

• 1. Read the first 8 paragraphs, stopping at "Representing a Rebounding Collision" (10min)
• http://www.physicsclassroom.com/class/momentum/Lesson-1/Momentum-and-Impulse-Connection
• key concepts:
  • F = m • a
  • or
  • F = m • ∆v / t
    • F • t = m • ∆v
  • If both sides of the above equation are multiplied by the quantity t, a new equation results.
    • Impulse = Change in momentum
  • Example: Solve the practice problem with the football halfback

2. #047B: Representing a Rebounding Collision Practice Problems

• We will solve example problem #1 together, and you'll do #2 and #3
• Impulse Momentum Chart

At Home Learning (HW)

1. If today was confusing, I made a video showing some of the key points here: LINK1

2. 47B: Complete the impulse momentum chart, as shown at the end of the video above. Link is above in 047A

3. 47C: Take notes/answer edpuzzle questions here:

Keep in mind that the impulse-momentum equation can be re-written to solve for the force of a collision like this: F = (m • ∆v)/t , as seen in the beginning of the video

(7:55) Impulse Introduction or If You Don't Bend Your Knees When Stepping off a Wall - EDpuzzle