Coefficient of Static Friction Lab

Today you are completing Lab: Coefficient of Static Friction. Please check your pre-lab #11 with me before moving on. Have me check off your lab when you are completely done, even if you have to finish at home over the weekend.

Your homework is Force TIPERs #4.

More Practice

Today we did another problem together on the board:

You then had more work time.

Homework: p.117 #30 & 51

Friction Practice

Today we first went through a problem together:

The rest of the period was yours to work, get help, or have your lab checked.

Homework: Friction TIPERs #3 + p.118 #39, 43

Friction

Today we started talking about friction:

Notes: Friction

We completed Friction TIPERs #1 in class; Force TIPERs #3 and Friction TIPERs #2 are homework. Email miss.volkening@gmail.com for copies.

Practice Problems

I feel that everyone needs to practice more force problems before we make them even more complicated by adding friction. So today was a work day. I checked your labs from earlier in the week while you worked on a new problem set:

p.114 MC #10 and Conceptual #1 + p.116 #21, 24, 26, 29, 38

Inclined Planes + More Practice

Today's Bellwork: What was wrong with the setup for the lab on Monday/Tuesday? Answer: we said that the net force on the cart was equal to the weight of our hanging object. That would only be true if the acceleration of the hanging object was zero, which it was not.

This means the actual, measured acceleration was smaller than the math predicted it would be. This effect is more pronounced at smaller cart masses (or larger values of 1/m). This tipped your best fit line for a vs. (1/m) down, decreasing the magnitude of its slope and therefore decreasing your calculated value for the mass of the hanging object.


After that big discussion, we went through how to deal with inclined planes. There is only one major change:



After you tip the axes you proceed pretty much the same as yesterday.

Hopefully you started your homework in class:

p. 117 #27 & 28

Solving Newton's 2nd Law Problems

Today we went through a method of solving word problems that involve Newton's 2nd Law:

Notes: Solving Newton's 2nd Law Problems

We may or may not have gotten to all of the examples, depending on the class. What we didn't get to we will finish tomorrow. We also may or may not have gone over what was wrong with the lab setup from Monday/Tuesday; if we didn't cover that in your class period today, we will tomorrow.

Homework is p. 116 #17 & 25

Newton's 2nd Law Lab

First we went over Force TIPERs #2 together. Then we went over the setup for your lab and finally you had the rest of the period to complete your lab:

Newton's 2nd Law Lab

This is another lab where I am checking your notebook, so don't actually turn anything in. Please have it ready to check by Friday, but sooner is also fine. We'll go over the error from the lab setup on Wednesday.

Newton's Third Law

Today we talked about the last of Newton's three laws as well as the normal force.

Notes: Newton's Third Law

Tomorrow you have a half day, but you won't actually be in class, so you have extra homework. Some of it you probably finished in class:

• Force TIPERs #1
• #6-9 on the Forces Non-Textbook Problems
• Force TIPERs #2 (we'll go over this one together next class, so please make an effort but don't turn in)

Here are the free-body diagrams for boxes A and B on the back of Force TIPERs #1:



Here are some sketches about normal force that made it up onto the board.

Newton's 2nd Law

Today we had a taste of Newton's Second Law:

Notes: Newton's Second Law

Homework:

p. 115 Problem #2
Forces Non-Textbook Problems #4 & 5

Forces and Newton's First Law

Today we started our forces unit with Newton's first law and free body diagrams:

Notes: Forces and Newton's First Law

We worked on a Net Force worksheet in class - it is homework if you didn't finish.

Homework is #1-3 on the Forces Non-Textbook Problems Bank.

More 2-D Practice

Today we had another work day to prepare for your test tomorrow. For a link to the practice test, its answers, and some videos showing how to solve similar problems, see yesterday's blog entry.

At the beginning of class today we solved a problem similar to #2 on the practice test. Here is how period 1 turned out:

2-D Kinematics Test Practice

We started today by going over last night's homework together. You do not actually need to turn that in.

You then started working on the practice test for 2-D kinematics; that test is on Friday. While you were working I may have checked off your lab from yesterday.

We are doing the same thing tomorrow.

2-D Practice Test

ABRIDGED Key:

Sometimes in the past I have made Khan Academy-type videos on how to solve various problems. I don't currently have any for these exact problems, but here are some similar problems:

Sort of like #3

Sort of like #4

Sort of like #7, but with numbers, which actually isn't very useful now that I think about it

Projectile Motion Lab

Today we are completing the Projectile Motion Lab. Note that this is done completely in your lab notebook; you are not turning this in, but it will be checked.

This is one of the launchers we used - many thanks to the University High School Foundation and Alumni Association for buying these.


Homework is the worksheet Projectile Motion TIPER #2 (email miss.volkening@gmail.com for a copy).

Finishing your lab is also homework.

Solving Projectile Motion Problems

Today we went through a process for solving projectile motion story problems.

Notes: Projectile Motion Problems

Here is the work for the airplane problem:

Here is the work for another problem in which someone jumps with a speed of 11 m/s at an angle of 20 degrees above the horizontal. We found the time it took to reach max height, the jumper's max height, and the horizontal distance the jumper went before coming back to his/her original height.


Homework is —Ch.3 (p. 80) #25, 27, 29, 30, 48, EXTRA CREDIT: #47. We'll be doing this lab on Tuesday (no school Monday).