DAY 23
WARM-UP: 10/13/16
Take out a sheet of paper. Rip it in half, and give half to your neighbor (or a mime).
Video Quiz
https://docs.google.com/document/d/1oNuoIPfD6E1097jHdYmki2Rw-X8TnqLkBvSbB8uIJPM/edit?usp=sharing
HOMEWORK
pg 71 #36, 38, 39
pg 82 #89
Notes and answer questions:
https://edpuzzle.com/media/5782be5d27ed9aaf13385ede
WARM-UP:
A construction worker accidentally drops a brick from the Empire State Building.
1. What force will cause the brick to accelerate?
2. What is the magnitude of acceleration due to this force (hint: this is a number) (hint #2: you may need to look this up)
3. What is the initial velocity of the brick?
4. Should we use
vf = vi + at or xf = xi + vit + 1/2at2
to find the velocity of the brick after 4s?
CLASSWORK:
A. NOTES - Free Fall:
Free fall is a special type of acceleration that only occurs when an object falls through the air in Earth's gravitational field. When solving free fall problems, we make the following assumptions.
Air resistance is negligible.
Objects behave as point particles. (think "particle models" from CH 2)
The acceleration of gravity is constant (9.8m/s2)
B. Demo
Free Fall Videos
- https://www.youtube.com/watch?v=xQ4znShlK5A
Is this ball accelerating? How can you tell?
Want more?
https://www.youtube.com/watch?v=JG0Fie-yZzc
Want to see what this will look like in college?
https://www.youtube.com/watch?v=47rLgSD8Qs0
C. Practice Problems
Individually, complete Pg 74, 42-46
Answers:
42: A: -39 m/s (upward is positive) B: 78 m
43: A: +39 m/s (downward is positive) B: 78 m
44: 8.3 m/s
45: A: 25.8 m B: 4.60 s
46: A: 2.2 m/s B: 0.45 s
D. LAB: How Fast is My Fastball?
Mr Alexander wants to know how fast you can throw an object upwards. Your team will design a lab to calculate the initial velocity of a thrown object. You will choose your materials and your experimental procedure. If you can provide evidence that you threw your object with a faster velocity than Mr Alexander can throw, you will receive extra credit for your team.
Abstract: What is the purpose of this lab?
Materials: What object did you use? What tools did you use to measure with?
Procedure: How did you set up the experiment and how did you take your measurements? Draw the experimental setup, including the path the object took through the air.
Data: Write down your measurements, preferably in a data table.
Calculations: Calculate the initial velocity of the thrown object. Show your work.
Conclusion: How fast did your team throw the object?