In CH 6, we will only cover section 6.1, projectile motion. For HW, or when you're done with the exam, read CH 6 pg 146-151, and create 3 multiple choice, true/false, yes/no questions for an in class Kahoot. Submit them to me in a google doc to j.alexander@tch.birminghamcharter.com by Sunday eve at 10PM.
Thanks for playing,
J.A.
#Goals: SWBAT...
1. draw a diagram showing force(s), lever arm, AOR, and θ
2. Solve problem including two or more torques
3. Describe the moment of inertia
4. Calculate the moment of inertia for a variety of shapes
WARM-UP & HW Check:(pg 210: 32; pg 205: 16-20)
For A-D, write the term's symbol, then define the term:
A. Torque: T; measure of force required to cause rotation
B. Force: F; a push or a pull
C. Mass: m; quantity of matter
D. Inertia: I; tendency of an object to resist change (aka, resist acceleration)
E. Solve: A student needs to use a wrench to remove a nut from a car.
Removing the nut requires a torque of 10N-m. The maximum force
the student is capable of exerting is 50N. Draw an FBD. Use G.U.E.S.S.
- At what angle to the lever arm should the student exert the force?
- What is the minimum length of the wrench the student must use to remove
the nut?
CLASSWORK:
1. HW Review, presented by your peers :)
32: Parker
16: Alexa
17: Alina
18: Enrique
19: Bryan
20: Joe
2. Review Inertia
http://www.flippingphysics.com/inertial-mass.html
3. Moment Of Inertia Pencil Activity
A. Materials: Pen or long pencil, two paperclips, two rubber bands, your brain
B. Procedure:
1. Recall the definitions of torque and force
2. Wiggle the pencil between your fingers. Do you need lots of force (and torque) to do this?
3. Add a pair of paperclips and rubberbands to the pencil, only a couple centimeters apart.
4. Do you need more force (and torque) to do this?
5. Move the paperclips as close to the end of the pencil as possible. Repeat #4.
4. Moment of Inertia Notes
A. Moment of Inertia is defined as: The resistance to rotation
B. Symbol: I (scalar, not a vector)
C. I = mr2
D. r is the distance of a point object from the AOR
E. Units: kg-m2
F. What happened to the mass in step #3. What about the measure of the inertia in step #3? Was this change of I directly or inversely proportional to the increased mass.
5. Practice Problems:
pg 208: 21-24, pg 225 #93-94
Tutoring available after school Mon, Tues, and Wed until 4:30. Lunch almost every day.
HOMEWORK:
Quiz on rotational motion (8.1) & single force and double force torques (8.2) this Friday.
pg 208: 21-24, pg 225 #93-94
21: The solution is on the board in B-77. Drop by for a look... :)
22: Hollow, but you have to write why :)
23. Different. Again, you explain why.
24. About A: 0.020kg*m2 About C: 0.080kg*m2
93: A; think about it. Email me if you aren't sure... j.alexander@birminghamcharter.com
B: 2.00m/s
C: 8x10-2 rad/s
94: 5.0x102 rad/s
pg 210 #34; pg 223 #76; pg 224 #83; pg 225 #95 & #98
34: 5.99 kg*m2
76:-7.54rad/s2
83: 0.048 kg*m2
95: think about it. Email me if you aren't sure... j.alexander@birminghamcharter.com
98: think about it. Email me if you aren't sure... j.alexander@birminghamcharter.com