DAY 55

WARM-UP

An ice cube slides without friction across a table at a constant velocity. It slides off the table and lands on the floor. Draw a sketch with two parts, a FBD and a motion diagram, of the ice cube at one point on the table, and one point in the air.

CLASSWORK

Goals: SWBAT set up a projectile motion problem

& find the x- and y-components of vi (initial velocity)

1. I want you to learn at your own pace for a while. Watch the video (LINK), and solve the problem along with Mr. P, but first read the questions below. Answers them while you're working. You should also look at the EdPuzzle notes here: http://www.flippingphysics.com/uploads/2/1/1/0/21103672/0062_lecture_notes_-_nerd-a-pult_-_an_introductory_projectile_motion_problem.pdf

A. What is the question you're trying to answer?

B. Too find the x-component, which trig identity do you use? What about for the y-comp?

C. Which equation do you use to find the change in time?

D. Which equation do you use to find the displacement in the y-direction?

pg 165 #56

#Goals: SWBAT...

1. Find the CM of any object

2. Solve problems with with torques, forces, and inertia components

3. Describe the Coriolis Force

WARM-UP & HW Check:

Now that you've watched the Flipping Physics lecture on Center of Mass...

A. Define "Center of Mass"

B. Look at the tapes hanging from the side-board. Which roll of tape will spin normally? Which won't? Why?

C. Watch me spin two pencils, one with a 15cm cardboard disk, and one without.

1. Which spins longer?

2. What does moment of inertia have to do with this?

CLASSWORK:

1. Center of Mass Notes & Activities

A. Definition: The CM of an object is the point on the object that moves in the same way that a point particle would move.

B. What's a Point Particle???

A point particle is where you could consider all the mass of an object to be located. (the CM)

(for example, if you had a 100cm ruler, a 20g mass at the 10cm mark, and the AOR was at 50cm, where would you place a second 20g mass on the ruler to keep it in static equilibrium? Where is the center of those two masses?)

C. Procedure for locating CM

1. Suspend an object from any point.

2. Draw a line straight down from the point of suspension

3. Repeat steps 1-2 from different points: one more time for a 2D object; two more times for a 3D object.

- Demo with Lacrosse stick

- Students try with paper

D. Stability and CM (If you missed today, look at Fig 8-13 on pg 212)

1. An object is stable as long as the CM is above its base of support.

https://www.youtube.com/watch?v=ajTyhbvMEAg

E. Conditions for Equilibrium

- An object is in equilibrium if:

#1: It is in translational equilibrium (Fnet=0), AND

#2: It is in rotational equilibrium (Tnet=0)

- Stable equilibrium (inherent stability) vs. Unstable equilibrium (inherent instability)

2. Putting it all together....Example Problem #5

Practice Problem: pg 215 36. An improved explanation to this is on the board in B-77

3. SKIP UNTIL MONDAY Coriolis Effect

https://www.youtube.com/watch?v=dt_XJp77-mk

https://www.youtube.com/watch?v=i2mec3vgeaI

4. Practice Test

Try: From the chapter: 27, 33, 34

pg 222-227: 48, 50, 54, 57, 65 (a moment of inertia problem), 68, 75, 82, 87, 88, 91, 97,

I will post answers to these Friday.

Tutoring available after school Mon, Tues, and Wed until 4:30. Lunch almost every day.

HOMEWORK:

CH 8 Exam is coming!! Wednesday 3/2 :-)

- Begin preparing your 1 page of notes

- Make sure your equation sheet is organized

HW: problem 36 & 37 pg 215

Practice Test: See #4 above. We will review on Monday - try the problems over the weekend. Big points :)