# AT Cycle 11

## 11/7 - 11/14

M 11/7

T 11/8

W 11/9

M 11/14

### π΄ 2: T 11/8a, π‘ 4: M 11/7 - massive pulley lab (1)

Daily Check-in: rotational dynamics

Today, we'll start with a brief check-in of rotational dynamics which you should have learned about in the video last night.

Then, we'll investigate rotational dynamics more by looking at a particular torque - that of friction.

Is frictional torque a good thing or a bad thing? Check out this video of a bow drill fire "engineer."

Sometimes, it's important to know exactly how much frictional torque there is in a system. We'll do a lab where we try to calculate the torque of friction on the aluminum disk mounted on the wall. This activity will require you to put together all of the pieces of rotational dynamics that we've been working with in the past couple weeks. The lab write-up is in β©οΈ Pivot Interactives "Finding the Torque of Friction (in-person)," although most of the lab will be done in person with the use of physical measurements and ποΈ Vernier Video Analysis. (If you are absent for this lab, you may do β©οΈ Pivot Interactives "Finding the Torque of Friction (virtual)" which does not require physical in-person measurements but rather requires you to make measurements from a video.)

Learning Goals of Massive Pulley Lab:

• Be able to draw a free body diagram of a complex system, and use it to solve Newton's Law problem.

• Be able to determine the moment of inertia of a physical pulley with the use of density.

• Be able to utilize available technology to determine the type of motion of an object.

• Be able to calculate the torque of friction on a rotating body.

• Be able to link the torque of friction to a real-life application, and learn about engineering solutions, evaluating cost-benefit.

Massive Pulley Lab Requirements:

• Large diagram of set-up with labeled measured distances

• Large free body diagrams of pulley and falling mass (make sure ALL forces are represented, remember that normal force and force of friction are components of the same force of contact)

• Calculations to find the moment of inertia of the rotating massive pulley

• Calculations to find the torque of kinetic friction

• Explain why the torque of friction is easier to find than the force of friction (or what we would need to measure in order to find the force of friction)

• Research on real-life applications and engineering solutions.

Safety considerations with the massive pulley lab:

Follow all directions in the lab. The Vernier caliper we'll be using has somewhat sharp edges, so be careful not to put it near anyone's eye or poke anyone's skin. In order to make measurements, you might have to be taller. Perhaps ask a taller student to collect measurements for your group or use the stepstool provided. Do not use a chair or lab stool to stand on. If you use the stepstool, have one other student assist you getting on and off. They should also stand nearby spotting you to make sure you don't fall. Don't do anything you're uncomfortable doing; call the teacher for assistance.

Homework: Finish the lab in β©οΈ Pivot Interactives by Tuesday, November 8th at 10pm. Quiz on center of mass, moment of inertia, rotational kinematics, and tipping - Tuesday, November 8th. Lab quiz on Massive Pulley Lab on Monday, November 14th.

### π₯β 2: T 11/8b, π¨β 4: T 11/8 - massive pulley lab (2)

Quiz on center of mass, moment of inertia, rotational kinematics, and tipping TODAY.

Today, we'll continue our lab on rotational dynamics.

Homework: Finish the lab in β©οΈ Pivot Interactives by Tuesday, November 8th at 10pm. Lab quiz on Massive Pulley Lab on Monday, November 14th.

### β€οΈ 2: W 11/9, π 4: M 11/14a - βοΈ massive pulley problems (1)

If anyone has not finished the lab, we'll finish that up today.

Today, we'll learn how to solve "massive pulley problems". We'll do these problems from Chapter 10:

Support: 49, 50
R
equired: 51, 53, 54, 55, 56, 69, 71, 98
Enrichment: 57, 87

We'll continue working on these problems next hour after the quiz.

Homework: These massive pulley problems are due Monday, November 14th at 10pm to βοΈ Google Classroom. Lab quiz on Massive Pulley Lab on Monday, November 14th.

### πβ 2: M 11/14, πβ 4: M 11/14b - massive pulley problems (2)

Lab quiz on Massive Pulley Lab TODAY.

After the lab quiz, we'll continue working through the "massive pulley problems" that we started last time. We'll do these problems from Chapter 10:

Support: 49, 50
R
equired: 51, 53, 54, 55, 56, 69, 71, 98
Enrichment: 57, 87

Homework: Finish any textbook problems you have not yet completed. These massive pulley problems are due Monday, November 14th at 10pm to βοΈ Google Classroom.

Watch the first 18 minutes of this video about "Rolling Without Slipping", please do so. This video is very important for the next lesson.