Fun With Angular Momentum

Today we looked at a bunch of real-life consequences of angular momentum. We learned a "magic" trick involving a ring and a necklace, played with a gyroscope, and finally we watched a couple of videos that use angular momentum to explain real-world stuff:

Why cats land on their feet - Smarter Every Day
Aerial Skiing - The New York Times

Homework: Ch.8 (p. 271) #58 & 72

I also had your practice test ready today, so you may have picked one up. You will have a multiple choice quiz thing on Friday, then you will receive a take-home test for the free response section. The free response section will be due on the following Thursday (so you'll have it for 6 days).

Here are the answers to the practice test:

Abridged answers

I also have some videos, but they are for an older version and some of the problems have changed.

#4
#5
#7 (PART C HAS CHANGED)
#8
#9 (energy method), #9 (dynamics method) (THIS HAS CHANGED)
#10
#11 (THIS HAS CHANGED)

Angular Momentum

First we did Plickers, and then we did this problem together:

The answer is b, but why? No energy is lost due to friction, since there would only be static friction (to make the ball roll) and static friction doesn't take energy out of the system the way kinetic friction does.

Next we took some notes about angular momentum. There aren't a lot of notes, and what there was ended up on the whiteboard. I also have notes from a past year when I was sick: Angular Momentum. Below you will find the answers for the example problems in that guide.

Suggested homework is p. 271 #55 (look up the mass, radius, and orbital radius of Earth with The Google) & 62

Finding the angular momentum of a bike wheel:


Finding the angular momentum with a clump of mud sticking to the rim of the wheel:

Finding the new angular speed of a star that has shrunk dramatically:

One last picture with all of the equations:

Momentum Test Practice

First you did your last Plickers, and then you took a 5-question, multiple choice quiz that I need for data. It won't hurt your grade.

The rest of the period was work time. Don't forget to get your last lab checked. Your last unit test is on your finals day.

Here is the momentum test practice. The key is here. Here are some of the video solutions:

#1
#2
#3

Impulse Due to a Variable Force

What is the change of momentum due to a force that is not constant? This was the question we attempted to answer today.

Notes!

Suggested homework: finish Momentum TIPERs #1 and do p.191 #8 & 15 . You will check this yourself - I don't want to grade it!

You might also have picked up a momentum test practice. The key is here. Here are some of the video solutions:

#1
#2
#3

Impulse

So far we've only talked about situations where momentum is conserved - that is, there are no outside forces. Today we talked about what happens when there are outside forces - the momentum changes! This change in momentum is called impulse.

Notes on Impulse

Video we watched

Suggested homework is p.191 Problems #9, 11, 13 + CONCEPTUAL Problem #12 (p.190)

Momentum in 2 Dimensions

Today we expanded our conservation of momentum problems into 2 dimensions.

Notes!
Here is the solution to the first example problem:

Here is a solution to the second example problem:

Suggested homework: p.194 # 49 & 51

Lab: Conservation of Momentum

Today you are completing Lab: Conservation of Momentum. This is your last lab grade for the semester.

Collisions

Today we talked about collisions, which are really just another kind of momentum conservation problem.

Notes: Collisions

The PhET collision simulator is here.

Suggested homework tonight is p. 192 #29, 31, 34a

You also need to complete the pre-lab for Lab: Momentum Conservation.

Conservation of Momentum

Today we had very few notes:

Notes: Conservation of Momentum

The rest of the period was yours to start your homework since it's a bit longer than yesterday's.

Suggested homework: p. 192 #25, 26, 27

Momentum Intro

Today we had one slide of notes and a bunch of practice problems:

Notes: Momentum Intro

Then you worked on your suggested homework: p. 190 #1, 3, 6, 7 (this might look like a lot, but they are all very short problems).

Work Day

Today you had time to work on your practice test. You will have a multiple choice quiz thing on Friday, then you will receive a take-home test for the free response section. The free response section will be due on the following Thursday (so you'll have it for 6 days).

Please continue to turn in your homework from this unit - remember that nothing from last week will be counted late since I was sick, but you do need to do that work eventually.

Here are the answers to the practice test:

Abridged answers

I also have some videos, but they are for an older version and some of the problems have changed.

#4
#5
#7 (PART C HAS CHANGED)
#8
#9 (energy method), #9 (dynamics method) (THIS HAS CHANGED)
#10
#11 (THIS HAS CHANGED)

Fun with Angular Momentum

Today we looked at a bunch of real-life consequences of angular momentum. We learned a "magic" trick involving a ring and a necklace, played with a gyroscope, and finally we watched a couple of videos that use angular momentum to explain real-world stuff:

Why cats land on their feet - Smarter Every Day
Aerial Skiing - The New York Times

Homework: Ch.8 (p. 271) #58 & 72

I also had your practice test ready today, so you may have picked one up. You will have a multiple choice quiz thing on Friday, then you will receive a take-home test for the free response section. The free response section will be due on the following Thursday (so you'll have it for 6 days).

Here are the answers to the practice test:

Abridged answers

I also have some videos, but they are for an older version and some of the problems have changed.

#4
#5
#7 (PART C HAS CHANGED)
#8
#9 (energy method), #9 (dynamics method) (THIS HAS CHANGED)
#10
#11 (THIS HAS CHANGED)

Angular Momentum

I am out sick again today, so I made a sort of guided notes thing: Angular Momentum. Below you will find the answers for the example problems in that guide.

Homework is p. 271 #55 (look up the mass, radius, and orbital radius of Earth with The Google) & 62

Finding the angular momentum of a bike wheel:


Finding the angular momentum with a clump of mud sticking to the rim of the wheel:

Finding the new angular speed of a star that has shrunk dramatically:

One last picture with all of the equations:

Impulse Due To a Variable Force

What is the change of momentum due to a force that is not constant? This was the question we attempted to answer today.

Notes!

Homework: Chapter 6 (p.191) #8 & 15 + CONCEPTUAL #11 (p.190). You will check this yourself - I don't want to grade it!

You might also have picked up a momentum test practice. The key is here. Here are some of the video solutions:

#1
#2
#3

Impulse

So far we've only talked about situations where momentum is conserved - that is, there are no outside forces. Today we talked about what happens when there are outside forces - the momentum changes! This change in momentum is called impulse.

Notes on Impulse

Video we watched

Homework is p.191 Problems #9, 11, 13 + CONCEPTUAL Problem #12 (p.190)

Momentum in 2 Dimensions

Today we expanded our conservation of momentum problems into 2 dimensions.

Notes!
Here is the solution to the first example problem:

Here is a solution to the second example problem:

Homework: p.194 # 49 & 51

Lab: Conservation of Momentum

Today you are completing Lab: Conservation of Momentum. Here is a picture on the board with some stuff. There happens to be some help with number 31 from the homework due today as well.

Homework is p.193 #36a, 37, 40

Collisions

Today we talked about collisions, which are really just another kind of momentum conservation problem.

Notes: Collisions

The PhET collision simulator is here.

Homework tonight is p. 192 #29, 31, 34a

You also need to complete the pre-lab for Lab: Momentum Conservation.

Conservation of Momentum

Today we had very few notes:

Notes: Conservation of Momentum

The rest of the period was yours to start your homework since it's a bit longer than yesterday's.

Homework: p. 192 #25, 26, 27

Momentum Intro

Today we had one slide of notes and a bunch of practice problems:

Notes: Momentum Intro

Then you worked on your homework: p. 190 #1, 3, 6, 7