DAY 68
#Goals: SWBAT...
1. Calculate Impulse & Force
2. Calculate change in momentum
3. Collect and Interpret velcity-time Data from a collision involving two carts
4. Compare system momentum before and after collisions
5. Calculate kinetic energy before and after collisions
6. Complete a professional lab report
WARM-UP:
1. Read the text, then with your group, answer the quiz questions in your warm-up.
http://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law
2. Write Newton's 3rd Law in your warm-up
3. Solve problem #13 on pg 238
CLASSWORK:
1. Conservation of Momentum Notes:
- What do we already know about momentum?
- sym: p
- vector? YES!
- the sum of the momentum before a collision (initial) is equal to....the sum of the momentum after a collision (final)
- We can express this in equation form as....
which is true for collisions and explosions (which is just another word for a collision)
(put formula here)
Demo Time!
(light cart & heavy cart)
More Notes...
- So when it this equation true? Always? Sometimes? Never?
- In everyday English, what does it mean to "conserve"?
- Two rules for conservation of momentum:
- Closed System: no objects may be lost or gained by the system
(think about the demo - what were the objects? Were they lost/gained?)
- Isolated System: the net external force on the system must be zero
2. Let's Try One :-)
You think you're so cool, so you light a firecracker and put it in the middle of the street.
The firecracker has a mass of 1.0kg, and breaks into two pieces (A and B) after the explosion.
Piece A has a mass of 0.25kg, and the velocity of piece B after the explosion is 12m/s to the right.
What is the final velocity of piece A?
3. Practice On Your Own....
pg 238 14-15
4. Momentum and Collisions Lab:
Your Final Product:
- Google Document with:
A. Answers to each question
B. Completed data table. (You can use a photo of the data table from your lab handout for this)
C. Calculations showing how you found the velocity and momentum for part 1, part 2, and part 3
(show an example of your work for one trial from each part)
D. Data must be shared with me by beginning of class Thursday. Lab Reports will be written in in class Thursday and due next Tuesday
Lab Report Contents & Grading
2pts 1. Introduction: in 2-4 sentences, describe how momentum and collisions are related
2pts 2. Objectives: (given on the lab handout - you can just re-type them)
5pts 3. Data table
10pts 4. Calculations (show your work for one trial from each part)
15pts 5. Evaluation: Write your answers to each question from Part 1, 2, and 3.
Notes: For Part 1, #3, and Part 2, #2, you can calculate the kinetic energy (before and after) for
one trial
HOMEWORK
pg 238 16-17
Google Doc with Lab Data shared with me by end of lunch Thursday
#Goals: SWBAT...
1. Pass the CH 9 Exam :-)
WARM-UP:
1. You have some review time today. The test isn't super long....
CLASSWORK:
1. Test today :-)
HOMEWORK:
1. We are covering Work and Energy next (CH 10).
2. Watch this! --> http://www.flippingphysics.com/work-intro.html
3. Complete the following:
A. What are the three most important learning concepts you saw/heard/learned from this video?
B. When Billy is holding the dictionary, is he doing work? Why or why not?
C. Are there any misconceptions pointed out in this video that you/your classmates might be confused by?
D. FYI: We will take notes on the first 40 seconds and on minutes 5:00-6:30 of the video in class Wednesday. If you want to get a head start, you can add the equations and
symbols to your table of friends...
E: The end is weird. I know.... Sorry.
F: There are some lecture notes here: http://www.flippingphysics.com/uploads/2/1/1/0/21103672/0134_lecture_notes_-_introduction_to_work_with_examples.pdf