Chapter 5 Practice Test

Today we simply practiced chapter 5 problems and admired each other's costumes. I also handed out the practice test:

Chapter 5 Practice Exam

Here are videos with solutions to the practice test:

#1
#2
#3
#4
#5

Your real test will be next Wednesday (and shorter than normal).

On Monday/Tuesday we will continue to work on the problems we started today. They are actually due at the end of class Monday/Tuesday, but you should do all you can this weekend and then get help on the rest during class:

Ch. 5 #2, 10, 11, 18, 20, 24, 38, 44, 45, 47, 53, 66, 68, 92

Work Done by a Varying Force

This topic is very difficult to get into a Powerpoint, so unfortunately I don't have one. Instead we used the whiteboard:

What you really need to know is this:

The work done by a variable force acting on an object that undergoes a displacement is equal to the area under the graph of F_x vs. x. 

So, graph F_x vs. x and find the area under the graph to find the work done by that force.

We practiced this with a ranking task, then we started working on homework problems.

Homework is Chapter 5 (p. 163) Problems #59, 60, 61.

Power

Today's topic was power! There actually isn't much to say about power, so there were a few notes with several practice problems:

Power!

Any leftover time was spent starting homework or checking your labs from last week.

You have a test coming up next Wednesday.

Homework: Chapter 5 (p. 162) #50, 52, 56. Use watts, not horsepower on #50 part b.

Spring Potential Energy

Springs! Springs are awesome and useful. Today we briefly introduced springs (we'll be doing more with them later) and derived an expression for the potential energy stored in a spring.

Here are the notes: Spring Potential Energy

Note that we derived Hooke's Law  by graphing F vs. x, either by using a physical slotted mass/spring set or with the PhET simulation (depends on availability of materials).

We also used these awesome direct measurement videos by Peter Bohacek:
Cart on ramp with spring
Cart launched by spring

Your homework tonight is Chapter 5 (p.160) #35, 39, 67

Energy Practice Problems

I want to make sure everyone is on track with all of the energy stuff we've done so far before we add more, so today we simply worked together on various energy problems from the book. So the homework below really was classwork, with whatever you didn't finish as homework.

Homework: Chapter 5, Conceptual #5, 6, 10 AND Problems #1, 4, 6, 7, 23, 89 (starts on pg. 157)

Work

Today we talked about work:

Work!

There were a few things that didn't end up on the powerpoint, like some diagrams and a demonstration.

You homework tonight is Chapter 5, Problems 8, 9, 13, 16

AP Practice Problems

Today we peer-graded the practice AP exam problems that we turned in just before and after fall break. The grade you will actually receive for these will be for participation only - some for doing the problems in the first place, some for grading other students' work. The point was to get experience with the problems and the way the points are allocated.

You were also given one more practice AP problem. This one is pretty difficult, and if you didn't finish it in class it is homework.

Bouncing Ball Lab

Today was my last District training, so I was out again. You worked on a lab:

Bouncing Ball Lab

Your homework is a worksheet with a skater jumping some alligators on the front and a roller coaster on the back.

Conservation of Energy

Today we talked about the conservation of energy and used it to solve problems that we previously could only solve with kinematics.

Conservation of Energy

Homework is Chapter 5 Problems 25, 32, 33, 37

Energy

Today we talked about energy - specifically, the two main kinds of mechanical energy, kinetic and potential.

Mechanical Energy

We also got a new seating chart; please contact me if you need to move.

Homework: Just answer these two questions:

1.Which is running faster: an elephant or a mouse with the same kinetic energy? Explain.

2.A 2 kg book sits on a 1.5 meter high table. Emily says its Ug is 29.4 J and Ben says its Ug is zero. Who is correct? Explain.

PSAT

Most of you are taking the PSAT in the morning (seniors are at a special lecture) and I will only see periods 5 and 6 today. I figure everyone will be pretty burned out by then, so we will be watching BBC: Connections (1978) - Faith in Numbers. 

Ch.4 Test

Welcome back from break! The first 35 minutes of class will be your time for last minute review. The last 70 minutes of class we will take the chapter 4 test.

No homework except to rest up and study for the PSAT which most of you are taking on Wednesday.

Practice Exam

Today we got the practice exam for the chapter 4 test:

Ch. 4 Practice Exam

Videos of the solutions are below:

Problem #2
Problem #3
Problem #4
Problem #5
Problem #6
Problem #7
Problem #8

We also got two more old AP exam questions, due when we get back from break.

Practice - In an Elevator!

We did more practice problems today -specifically, what would a bathroom scale say in an accelerating elevator? We did one problem together:

Then we worked on a Ranking Task worksheet with the same kind of problems, and finally we worked on an old AP Physics problem (2003B1).