# AT Cycle 8

## 10/19 - 10/25

**W 10/19**

**Th 10/20**

**F 10/21**

**T 10/25**

### π΄ 2: Th 10/20a, π‘ 4: W 10/19 - πͺ ladder lab (1)

Today,, we'll investigate the situation of a ladder leaning against a wall. We'll start with a short video about ladder safety. We'll use this to generate some questions about ladder safety. We'll **use what we know about static equilibrium to figure out where we can stand on a ladder and feel safe**. You will work as collaborative team members to **build a couple different models of the situation and make predictions about safety**. Then, we'll test your Ladder Lab models with a few questions. You'll go through the **iterative process of engineering your ladder model** to correct any weaknesses. You'll answer a few more questions to make sure your model works well. Finally, you'll answer the ultimate question about the real-life safety of ladders by researching some specifications of real ladders and you'll consider some design choices that could make the ladder safer.

*Lab Safety: During our ladder lab, we will be leaning a model of a ladder up against a wall and sometimes hanging masses off the ladder. The ladder may be in a precarious position, so please make sure not to place your hand under the ladder, as the ladder could slide and fall on your hand or fingers. Also, since you are using masses, be careful that the masses do not fall off the table as that could cause injury if they land on someone. Don't attempt to climb a ladder at home without supervision.*

**Handout**: Ladder Lab

**Homework**: Finish creating your mathematical models on page 1 of Ladder Lab if you have not already done so. We can test your models next time. Make sure you've completed Hard Torque Problems due to βοΈ Google Classroom by Wednesday, October 19th at 10pm.

### π₯ 2: Th 10/20b, π¨ 4: Th 10/20 - πͺladder lab (2)

We'll test and **evaluate your ladder models**. Do you think this is a good strategy to ensure safety?

*Lab Safety: During our ladder lab, we will be leaning a model of a ladder up against a wall and sometimes hanging masses off the ladder. The ladder may be in a precarious position, so please make sure not to place your hand under the ladder, as the ladder could slide and fall on your hand or fingers. Also, since you are using masses, be careful that the masses do not fall off the table as that could cause injury if they land on someone. Don't attempt to climb a ladder at home without supervision.*

**Homework**: Finish the Ladder Lab due in class Tuesday. *Study for QUIZ on static equilibrium problems **Tuesday**, October **25th**.* Watch the following videos:

### β€οΈ 2: F 10/21, π 4: T 10/25a - tipping

Today, we'll talk about tipping problems from Chapter 12 in the textbook. You'll learn **how to determine if an object will tip**. For tipping problems, you need to really THINK about the situation as you're drawing your free body diagram. You also need to think about the best choice of fulcrum. Finally, using line of action usually helps.

Required: Giancoli #38, Halliday #25+, 35, 41, 56 (not really a tipping problem)

For #25, also find the force required if the force is applied at the very top of the wheel.

**Homework**: Finish the Ladder Lab due in class Tuesday. *Study for QUIZ on static equilibrium problems ne**xt hour - **Tuesday, October 25th.*

Watch the following video which has to do with tipping. The red crosshairs on the box represent the object's center of mass. Notice that the box tips when the center of mass goes past the the support base. How can use geometry to find the incline angle at which the box will tip based on the location of the center of mass?

### πβ 2: T 10/25, πβ 4: T 10/25b - static equilibrium & tipping

*QUIZ on static equilibrium problems on TODAY!*

With any time remaining, you'll finish the tipping problems in the post above.

**Homework**: Finish any of the above problems due in βοΈ Google Classroom on Tuesday, October 25th. Then, watch the video below. If you've taken calculus before, this may be review, but watch it anyway from a physics perspective. If you have not taken calculus before, you might watch this more carefully. We will be starting to review the calculus necessary for this course next class. If you are confused by this video, don't worry; we will address your questions next time by going over the material again, but it is important to have more than one exposure before understanding.