Open House is tonight, which means I could really use your help keeping the tables and room clean today. At the end of class, if you would please clean up the area around your station, and push in your chair and any chairs in your area, I'd appreciate it. Thanks! Mr. A
#Goals: SWBAT...
1. Solve Impulse and Δp problems
2. Measure in SI the momenta involved
3. Interpret Data from a collision.
4. Draw Conclusions that support the law of conservation of momentum.
WARM-UP (ends at 12;35):
A. What is the formula for momentum? (don't forget vector symbols)
B. What's the formula for impulse? (HINT: check your equation chart, notes, or Day 63's Bozeman Science video if you get stuck)
C. Watch the video, and answer the five questions below https://www.youtube.com/watch?v=fdeH6Ksedwk
Recall: 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?
When our video presenter jumps from the table, he begins falling.
2. 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. HW Review Video
http://www.youtube.com/watch?v=GwE3Y2hnubw
2. Practice Problems
pg 233 #3, 4, 5
pg 250 #33, 34, 36, 47
2. Momentum Notes:
Copy the definition for momentum into your notes:
Momentum - the force or energy with which a body moves, measured as a product of its mass and velocity.
If there are no forces acting on an object, its linear momentum is constant.
What about mass - is mass constant or can an object's mass change?
An object's mass cannot be changed, therefore, if the momentum is constant, velocity must also be constant.
3. LAST DAY OF YOUR Momentum Lab
I will be checking your progress online today at the end of class, and making comments this afternoon.
It's your job to get it all done in class, or divide up responsibilities equally and get it all done by the due date, Monday 03/20
http://www.glencoe.com/sec/science/internet_lab/olc.php?olcChapter=809
Your Final Product:
- Google Document with Title, Names, Period, and...
A. Hypothesis
B. Materials
C. Answers to each question from: Analyze, Conclude & Apply; Going Further; Real-World Physics sections
D. Completed data table.
HOMEWORK:
1. Complete pg 235 # 8 & 9
2. Complete lab
#Goals: SWBAT...
1. Relate Newton’s third law to conservation of momentum.
2. Recognize the conditions under which momentum is conserved.
3. Solve conservation of momentum problems.
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 #67 on pg 251
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!
(skateboard and something heavy)
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 13-17
Tutoring available after school Mon, Tues, and Wed until 4:30. Lunch almost every day.
HOMEWORK:
1. Did you turn in your momentum lab? If not, watch out when the rapture comes... (turn it in - it's late...)
2. Complete pg 238 13-18
Answers to HW:
13. 1.1m/s
14. 0.034m/s
15. 1.2 x 103 m/s
16. 2.8m/s
17. 6.7 m/s
18. 2.0m/s in the _________ direction