Mopping Up the Semester

Our last day of regular class was what I like to call a mopping-up day:

You can email me for electronic copies of the extra credit.

Momentum Practice Problems

Today we worked on our last set of problems for the semester, which is due next class:

Chapter 6 #59, 66, 74

You also received the practice test for the free response section of the final. Remember that the multiple choice section will have at least 8 problems and could cover anything from the entire semester. The best way to study for the multiple choice section is to review the multiple choice problems from previous tests and practice tests.

Here are the video solutions for the free response practice problems:

#1
#2
#3
#4

Conservation of Momentum in 2 Dimensions

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

Notes!

Here's another method of solving the practice problem in the notes:


We then started working on the the homework:

Chapter 6 (p. 193) #38, 49, 51

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, 17, 68

Egg Drop Lab

Today you built a device to keep an egg from breaking when dropped off the visitors' bleachers. Here are the instructions that were on the board:

Your homework is Chapter 6 #12, 14, 19 + one paragraph explaining why your egg did or did not break (using momentum concepts) and how you could improve your design. Turning in this paragraph gets you participation points for the lab.

Impulse

So far we've only talked about situations where energy 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

Next class you will be making a device to save an egg from breaking after a fall from the visitors' bleachers. You need to bring your own supplies if you can since mine are limited. It would also help if someone in your group brought an egg. After we test your device you will turn in a short explanation of why your egg did or did not survive using momentum concepts.

Homework for the weekend is Chapter 6 (p.191 ) Problems #9, 11, 13 + CONCEPTUAL Problem #12 (p.190)

Conservation of Momentum Problems

Today we just worked on various conservation of momentum problems. Whatever you didn't finish in class is homework and the whole thing is due tomorrow.

Chapter 6 (p.192) #21, 22, 25, 26, 27, 33, 37, 40, 41

I also checked your Ballistic Pendulum labs while you were working.

Finally, does anyone have an old egg or two? I want to do a demonstration tomorrow but I don't eat eggs so I don't have any on hand and I don't want to buy a whole container of eggs if I can avoid it. You might even get them back...maybe :)

EDIT: First period convinced me that we should do the egg drop project, so we're going to need 40 eggs total. If you bring an egg, write your name and period on it and you can use it for your project.

The goal will be to keep an egg from breaking when it is dropped from the visitors' bleachers. We'll have your modular day to build it, drop it, and write an explanation (using physics) about why your egg survived (or didn't). You can use anything you want except parachutes. The group whose egg survives with the lightest mass contraption (weighed with the egg inside) wins a prize (snack).

I have only limited supplies (pipe insulation, one bag of cotton balls, some quilt batting) so I ask that groups gather and bring their own supplies so that only the students that truly cannot afford it can use my stuff.

Ballistic Pendulum Lab

Today you completed the Ballistic Pendulum Lab in your lab notebook. You need a procedure, data, and answer (what is the launch velocity of the silver ball). It will be checked during class tomorrow.

Here is a running list of things people discovered about the lab apparatus (I'll update as needed):

• The mass of the pendulum bob is 86.2 g; don't try to measure that yourself
• Pull on the circular knob at the back to cock the launcher, not the stick-like knob near the front
• Flick the stick-like knob near the front of the launcher to launch the ball, not the circular knob at the back
• Don't use the third notch
• Cock the launcher and THEN load the ball
• If your table is uneven the launcher is less likely to work. Use the counters around the outside of the room
• The angle indicator is off on some of the launchers; check yours and compensate as needed

Conservation of Momentum

I didn't have access to my desktop at home this weekend, so I had to use a Chromebook and therefore Google Slides for our notes today (so no fancy animations):

Conservation of Momentum

You may have started working on your Ballistic Pendulum Lab, which you will be completing and is due on Wednesday. Your homework tonight is to be ready to take your data on Wednesday (whatever you need to complete to be ready).

Reminder: there are only a few weeks left in the semester; I would appreciate make-up work to be turned in sooner rather than later. Chapter 7 retake tests are also ready to go, although I will not have your tests ready to hand back to you until Wednesday (probably, though maybe earlier).