DAY 77
#GOALS: SWBAT...
1. Define momentum, its symbol, and its units.
2. Explain how the total momentum before a collision relates to the total momentum after a collision for elastic and inelastic collisions.
3. Calculate momentum for various situations.
WARM-UP
Why can't you "run from momentum"?
Momentum Definition:
Symbol:
Equation:
Units:
Is it a Vector?
CLASSWORK
077A: Momentum Intro
1. How did the book(s) cause the skateboard to move?
2. Did the books have momentum prior to the collision? Did the skateboard?
3. Post collision, did the book(s) and the skateboard have greater speed, less speed, or the same speed as the book(s) before it(they) hit the skateboard?
4. Why did the two book/skateboard combo roll faster post collision than the one book/skateboard combo?
077B: Prior Knowledge Inventory: Momentum
Paraphrase the statements below, then evaluate them as either true or false.
1. Momentum tells us how much energy an object has.
2. It is possible for a small car to have the same momentum as a large truck if the car moves very fast.
3. Momentum is the product of an object's mass and its speed in a straight line.
4. If a 70 kg human is walking at 2 m/s, her momentum is 35 kg/m/s.
5. If an object is not moving, it still has nonzero momentum because it still has mass.
077C: Momentum: Guided Reading
Go to the following website: Physics Classroom: Introduction to Momentum.
Read the tutorial. You may stop at “Check Your Understanding”. Answer the following questions in complete sentences. For fill-in-the-blank questions, you should copy the entire sentence and fill in the blank. Your answers to these questions will be your notes for this section, so the more thoroughly you answer the questions, the better prepared you will be.
1. What is momentum?
2. How is the Physics definition of momentum different from the “colloquial” use of momentum? (Colloquial means the everyday use, for instance saying that our football team has built up momentum through all their recent wins.)
3. How is momentum calculated?
4. What is the symbol for momentum?
5. What are the standard units for momentum?
6. Momentum is ____________ proportional to an objects mass and its velocity, meaning that if either the mass or the velocity increases, the momentum will _______________.
7. What do we mean when we say that momentum is a “vector”?
Practice: Answer the following questions. For calculations, you should show all of your work.
8. A 300 kg tiger is prowling with a velocity of 3 m/s westward. What is the momentum of the tiger?
9. A car and a bicyclist are both moving at 10 m/s. Which has more momentum? Explain.
10. Why does a rocket have such a great momentum even if it is moving at a slow speed?
11. You and a friend are discussing momentum after class. Your friend believes that objects with more mass always have a greater momentum. After thinking about today’s lesson, you tell him that you can come up with two different ways that a baseball and a truck could have the same momentum. What are the two possible ways?
12. A 1000 kg car is moving south with a speed of 20 m/s.
a. What is the momentum of the car?
b. How fast would a 100 kg bicyclist have to travel in order to have the same momentum?
c. How fast would a 10 kg bowling ball have to travel in order to have the same momentum?
d. How fast would a 0.1 kg baseball have to travel in order to have the same momentum?
LEARNING AT HOME (HW)
1. Complete 077C
2. Bring answers to 25 questions from 76A to class
3. YoU cAn SaVe ThIs ViDeO uNtIl ToMoRrOw If YoU'd LiKe. We won't use the material it covers until Thursday. 077D: Watch the video, take notes, and answer edpuzzle questions
Lecture Notes: https://www.flippingphysics.com/uploads/2/1/1/0/21103672/0175_lecture_notes_-_force_of_impact_equation_derivation.pdf
EdPuzzle: https://edpuzzle.com/media/5886407a75bd5044d59c8ed0
Goal:
SWBAT
1. Define Refraction
WARM-UP
1. Describe the straw's appearance.
2. Why does the straw appear split?