Friction + Inclined Planes

Today we first went over Friction TIPERs #4 and traded papers to give feedback. That does not need to be turned in.

Later we did one practice problem that combines friction and inclined planes, then you started on your homework:

p.117 #30 & 51
+ complete the pre-lab for our lab tomorrow: Finding the Coefficient of Static Friction

Friction Practice

Today I was out, so you practiced some friction problems on your own. Whatever you didn't finish in class is homework.

Friction TIPERs #3
Friction TIPERs #4
p.118 #39 & 43

Friction

Today we started talking about friction:

Notes: Friction

We completed Friction TIPERs #1 in class; Force TIPERs #5 and Friction TIPERs #2 are homework. Email miss.volkening@gmail.com for copies.

Work Day - Practice Problems

Because of the pep assembly (and because everyone needs to practice more force problems) 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

Practice + Inclined Planes

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.

Homework is p. 116 #17 & 25 + what was wrong with the lab setup on Monday/Tuesday?

Newton's 2nd Law Lab

Today we used Newton's 2nd Law to find the mass of an object without relying on a scale.

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.

Challenge: something was wrong with the setup - can you find it? We'll talk about it Wednesday, but it's the reason more mass on the cart worked better.