DAY 66
WARM-UP (10 min)
Goal: SWBAT identify the correct equation by using the given/unknown info.
For today, you'll have a set of given info, be tasked with choosing the correct equation from your equation chart, and rearranging the equation to solve for the unknown. Show your work by starting with the equation in its normal form, and show your steps while you rearrange.
0. given: momentum, mass unknown: velocity (we'll do this one together)
1. given: velocity, momentum unknown: mass
2. given: impulse, force unknown: change in time
3. given: initial momentum, change in time, force unknown: final momentum
4. given: force, change in time, mass, initial velocity unknown: final velocity
For the following, have I described an elastic or inelastic collision?
5. Two carts are rolling. When they collide, they stick together.
6. Two carts are rolling. When they collide, they bounce off each other.
** I'm checking your Day 64 assn (pg 233 #3, 4, 5; pg 250 #33, 34, 36, 47; pg 235 # 8 & 9)**
**Your online lab rough draft is due today. Check the video below for assistance with common errors**
CLASSWORK
1. Collecting Data to Measure Momentum
Q. How do I do this? A. Think about the equation of momentum - you need to find...
__________ & ___________.
Finding m is easy. You use a _________. Finding v is more challenging, but we've done it before
using your video-camera, a stopwatch, and a ruler.
How would you collect v data from this video? LINK
2. Online Lab Updates
Rough draft due today. Complete labs, correct or not, get 10/10.
Final Draft due Tuesday next week.
STILL STRUGGLING WITH our online lab? This might help...
So, in Part 1, you're pushing one cart into a stationary second cart. For both those carts, their initial velocity is the velocity they have prior to the collision. One cart has a velocity around 0.2 to 0.4m/s, and the other cart is at 0m/s. Here's how you measure velocity: VIDEO LINK Since the carts stick, you have to add their masses for the 'departing' portion of the problem.
In other collisions, you may encounter a situation where the cart you pushed probably stopped, and the only other cart started moving. The velocities of the carts after the collisions would be your final velocities. One would be 0m/s (or very close to zero - some of the carts started moving backwards....) and the other would be somewhere around 0.2-0.4m/s.
Here's a video showing this: https://www.youtube.com/watch?v=IQTpaYJHZNchttps://www.youtube.com/watch?v=IQTpaYJHZNc
For your lab write-up, it should look like this: VIDEO LINK
3. Lab & Practice Problems:
We will rotate through today's lab.
Half of you will work on practice problems: pg 251 56-61 & 67
Answers:
56: 0.013s
57: a) -14kg*m/s b)-3.2 x 104 N
58: 74 kg*m/s 1.0 x 101 m/s
59: a) 2.0 x 104 kg*m/s b) 1.3x103N
60: -1.2x103N
61: -6.0x101N
67: a) -5.1 kg*m/s b) -1.0x102N c) -1.0x101N
Half of you will work on today's lab. Aim to collect data for three runs of Part 1, and use them
We will switch at 1:24
HOMEWORK
Complete the practice problems from above.
Review today's warm up and the practice problems to prep for our quiz on Friday.
Solutions to practice problems (only check this if you get stuck/get the wrong answer).
http://www.youtube.com/watch?v=ESwnzVZm5tA
#Goals: SWBAT...
1. Solve conservation of momentum problems.
WARM-UP:
1. A 95-kg fullback, running at 8.2 m/s, collides in midair with a 128-kg defensive tackle moving in the opposite direction. Both players end up with zero speed.
a. Identify the “before” and “after” situations and draw a diagram of both.
b. What was the fullback’s momentum before the collision?
c. What was the change in the fullback’s momentum?
CLASSWORK:
1. Quiz
2. HEADS UP! Exam on CH 9 next week (Monday)
Practice Test is below...
3. Predict the Outcome...
http://www.physicsclassroom.com/mmedia/momentum/2di.cfm
Notes: Conservation of Momentum in 2-D
- The law of conservation of momentum holds for all isolated, closed systems, regardless of the number of objects or dimensions.
- Copy the procedure for solving the practice problem
4. Try a few problems
Pg 243 22-23
5. Practice test for HW:
pg 250-254
Problems 33; 34, 38, 40, 49; 56; 59; 61; 68; 72; 74; 80
Tutoring available after school Mon, Tues, and Wed until 4:30. Lunch almost every day.
HOMEWORK:
Try practice problems #33; 49; 59 for full credit.
Try the rest for extra credit :)