# HP Cycle 16

## 12/8 - 12/13

**Th 12/8**

**F 12/9**

**M 12/12**

**12/13**

### π’ 5: Th 12/8 - Newton's Laws review

Today, we'll spend the period reviewing for your upcoming exam on Newton's Laws in one dimension. Review your submitted classwork problems, or do additional textbook problems or any of the optional problems from this unit. Remember that you will have two options on the exam:

Option 1 (comprehension) problems will come from any of the required classwork problem sets and will earn a maximum of 80%.

Option 2 (application) problems will be new problems that you've never seen before.

Both of these options are designed to be roughly the same difficulty level; the only difference is that you've seen the Option 1 problems before. My recommendation with these two options is that you should read the option 2 problem first. Then, if you decided it's too difficult, then do the option 1 problem. If having the two options is too stressful for you, then just plan on doing all option 2 problems.

There will be three free response questions for which you will be able to choose from Option 1 or Option 2. The directions will be written at the beginning of each problem, but for your advanced review, I have reproduced them here:

*Make sure to draw free-body diagrams of ALL objects, show your choice of coordinate system, write Ξ£F statements, show all algebra with variables, and solve! Only plug in numbers in the last step of every problem. Units on ALL numbers. You may use either g = *9.8*m/s*^{2}* or g = *9.81*m/s*^{2}*. You may use the same single free body diagram throughout a particular problem if appropriate. Three sig figs in all of your answers please. Write your answer with units on the line after the question. *

**Optional Challenge Problems**: Two Block Problems #1, 2, and 4. SOLUTIONS

**Homework**: *Assessment of all of Newton's Laws next class - Friday, December 9th.*

### π΅β 7: F 12/9 - Newton's Laws 1-D Assessment

*Newton's Laws 1-D Assessment Today!*

**Homework**: None

### π©β 5: F 12/9 - Newton's Laws 1-D Assessment

*Newton's Laws 1-D Assessment Today!*

**Homework**: Review any of the vector notes that you took and the videos from the last post.

### π¦ 7: M 12/12 - adding vectors

Today, we'll see how we can add vectors that are not at right angles to each other. We will learn to break vectors into x- and y- components and why that is useful to us. We'll try this example problem together:

**Homework**: If you'd like to review more on vector addition, you can watch these videos:

For the example in the next video, imagine that two people are pulling on an object placed at the origin. The red person pulls with a force of 6.32N at an angle of 18.4 degree, while the blue person pulls with a force of 5.66N at 45 degrees.

The goal is to find the resultant force. In other words, instead of two people pulling in different directions, if there were one strong person who could exactly replicate the net force on the object, with what magnitude and direction of force would the strong person exert on the object to get the exact same result? Start this problem by first drawing a picture and by then finding the x- and y-components of each of the force vectors. Then watch the video below.

### π 5: T 12/13, π 7: T 12/13 - π static equilibrium lab

Today, we'll look at **"static equilibrium" problems - where the forces are balanced**. We'll look at how Newton's Second Law acts in two dimensions by performing a lab where we try to find the mass of a mystery object using two dimensional forces. See the figure for set-up of the "y-tension problem." In these types of problems, we'll look at making Ξ£Fx=0 and Ξ£Fy=0, but some of the forces will be at angles.

If you have any trouble understanding the calculations here, check out the following video below. The strategy is to draw a free body diagram of the knot. (If the knot is made out of ideal or massless string, it does not have a force of gravity on it.)

**Homework**: *Quiz on dynamics in 2-D on Monday, December 19th. *If you'd like to get ahead, check out the π Mastering Physics problems in the next post.