# Tag Archives: AP1

## AP1 Unit 6: Energy Transfer Model

So far, we have always started this unit with a quick lab to determine the relationship between the stretch of a spring and the force the spring exerts. The result of the experiment giving us Hooke’s Law: $F_S = - k \Delta x$

I’ve contemplated moving that lab to an earlier unit, likely Unit 4 after the gravity lab. So far, I have kept it at the start of this unit.

After the spring lab, we quickly proceed to the paradigm activity for this unit. You can read about that here.

The first step in deploying the model is this video that explains how to use energy diagrams. I haven’t had time to properly introduce the pie charts, but so we jump straight to energy diagrams.

We begin with worksheet 1, which has the students create the energy conservation equation from the energy diagrams for various events. For those familiar with energy diagrams, either from my previous post, Kelly O’Shea, or modeling materials, you’ll see that I’ve recently modified what my students are doing. In an effort to make them similar to momentum diagrams, I moved the identification of the system to the left side of the diagram. I then add a Force vs. position diagram between the two bar charts when the system is open, similar to the Force vs. time graph for momentum diagrams.

In worksheet two, we now add in doing calculations to the mix. The students now need to solve similar problems, but are now given numerical values.

After that, we usually are ready to celebrate Festivus!

We celebrate this holiday with the “Feats of Strength!” I begin by asking the students who is the most “awesome” at lifting a bag. Usually at least one student will ask me to clarify what I mean by most awesome. After discussion and prompting from me, we usually settle on an “awesome-ness” factor, designated A as some arrangement of: $A = \frac{m g \Delta y}{\Delta t}$

At some point, the students notice that energy is in the numerator of this factor. At some point along the way. we rename this factor “power.” Before we get to that, I try to ask them what name we could give to this quantity. We usually start taking about “awesome” videos on youtube, such as Kobe Bryant jumping over a pool of snakes:

Usually, as Kobe is in the air, at least one student will say, “Whaaaattt!”

Usually followed by, “That can’t be real!” If a student doesn’t say it, I’ll lead them to it, but once they say, “Whaaatt!” they’re ready. I let them know that the unit of power is the watt.

I now reveal the two challenges for the Feats of Strength, the Bag Lift, and the Ascension of a Flight of Stairs. The students each must compete, but they don’t have to try too hard if they don’t want. In the end, they must calculate their power output in watts. I do this, so that the students get a physics sense of the SI unit of power. We usually wrap up the activity by asking how many of the students could have powered a 100 W light bulb or a 1200 W microwave oven.

From there, we progress to worksheet 3 which now includes calculations of power along with the energy diagrams. After that it’s time to review and take the test. After this unit test, we review for our midterm, take that midterm, and go off for Christmas Break.

## AP Physics 1 Syllabus

I recently was able to get my syllabus approved by College Board. The approval number is # 1485588v1 Authorized

## AP1 Unit 3: Momentum Transfer Unit

This third unit on the MTM is the first significant deviation from the traditional modeling framework. I expect it to take approximately two weeks. It will begin with two carts “exploding” apart and whiteboard meetings to analyze the results (ratio of masses of carts -> ratio of velocities of carts).

From there they will proceed through some of the modeling materials for the Momentum Transfer Model as provided by the Modeling Materials. The main focus of the unit will be that momentum is a quantity that is swapped between objects, depicting those swaps with “interaction diagrams” (formally called system schema) (labels of types of forces withheld during this unit), and momentum diagrams (IF charts). Also along the way, I will try to emphasize the similarity between displacement (being term for a change in position) and impulse (being the term for change in momentum).

The first worksheet is the same as the first worksheet from the Modeling Materials. It looks at mainly qualitative events and has the students determine relative momenta or impulses. We then look numerous collisions to see if momentum is conserved in collisions as well as the explosions seen in the lab.  We skip the second worksheet provided by the Modeling Materials, as most of these problems focus on calculating impulses from Force & time. These types of problems will be address later in the UFPM unit.   The new second and third worksheets use momentum diagrams to solve collision problems. We end with additional problems for review.

The students goals for this unit are:

SWBAT

1. create an interaction diagram including the identification of the system.
2. create a momentum diagram (IF diagram) for an event.
3. interpret a momentum diagram by creating a mathematical model of an event.
4. correctly solve problems involving an exchange of momentum.

## ΑP1 Unit 2: Constant Acceleration Particle Model

This second unit on the CAPM will proceed along the traditional modeling framework. I expect it to take approximately two and a half weeks. It will begin with ball rolling (or cart sliding) down and incline plane and whiteboard meetings to analyze the results. The only change from the traditional progression will be to first complete the “Graphing Practice” worksheet from the Scientific Methods unit.

From there they will proceed through the modeling materials for the Constant Velocity Particle Model as provided by the Modeling Materials. The first worksheet allows them to analyze additional data sets similar to what the saw in the lab. The second worksheet has the student create motion maps, position-time, velocity-time, and acceleration-time graphs for more complicated ramp systems. Worksheet 3 focuses on analyzing position-time and velocity-time graphs. Worksheet 4 has the student solve quantitative problems. We end with additional problems for review.

The students goals for this unit are:

SWBAT

1. create and interpret graphical and mathematical representations of objects moving with constant acceleration.
2. can correctly differentiate between acceleration and velocity.
3. correctly interpret the meaning of the sign of acceleration.
4. solve kinematic problems involving constant acceleration.

## AP1 Unit 1: Constant Velocity Particle Model

This introductory unit on the CVPM will proceed along the traditional modeling framework with only a few additions. I expect it to take approximately three weeks. It will begin with the Buggy Lab and whiteboard meetings to analyze the results.

From there they will proceed through the modeling materials for the Constant Velocity Particle Model as provided by the Modeling Materials. Thus the new worksheet 2 will be a worksheet that focuses on the students converting between the position-time graphs, motion maps, and verbal descriptions. Worksheet 3 will then add velocity-time graphs to the mix. Worksheet 4 brings back data analysis and converting to the other representations. Worksheet 5 does the same, but for slightly more difficult situations. We end with additional problems for review.

For those using Standards Based Grading, the first draft of may standards is as follows:

Students will be able to (SWBAT):

1. design an experiment that properly controls variables
2. report measurements and calculations with proper precision
3. develop a mental model that correctly explains and predicts an event
4. algebraically solve an equation for a given variable.
5. create a scatter plot of independent and dependent data points
6. linearize data points
7. create a mathematical model of a graph.
8. create and interpret graphical and mathematical representations of objects moving with constant velocity.
9. distinguish between position, distance and displacement.
10. solve problems involving average speed or average velocity.

I’m fully aware that this is a long list of standards, and quite possibly too many standards. Any feedback on whether or not the list should be adjusted (and how) would be greatly appreciated.

## AP Physics 1 Storyline

As I prepare for the transition to the AP 1 course, I’ve taken this school year (2013-2014) to begin trying some things out. Based on what I’ve tried, here is the storyline I’m going to use with my AP 1 students next year. Before I get into the details, I do plan to use Modeling Instruction throughout the course. If you haven’t had the chance to take a workshop, do yourself a favor and find one. Also, I plan to make future posts providing more detail for each unit.

We begin the year jumping right into the Constant Velocity Particle Model (CVPM). The students at my school come out of chemistry, and for the most part have decent skills when it comes to doing labs. Although we don’t use modeling in our other science classes, they have a majority of the basic skills. So I save a little time by skipping the Scientific Methods Unit.

Our second unit, then progresses to the Constant Acceleration Particle Model (CAPM). As I mentioned, I plan to give more detail later, but for those familiar with the materials provided, I’m not doing that much different from those documents.

The third unit is where I make my first big adjustment from the traditional modeling curriculum. After reading numerous posts from some of the bloggers I admire the most (read Momentum is King, Kelly O’Shea’s blog, and more recently Mazur’s Physics Textbook), I decided to try out teaching momentum before Newton’s Laws. During this third unit, Momentum Transfer Model (MTM), we focus on interaction diagrams and the swapping of momentum as the mechanism of physical interactions. We stress the choosing of a system, and that momentum swaps within the system, or swaps out of the system as an impulse. In the end, we are building the concept of Newton’s Third Law. In addition to what I call Interaction Diagrams (others call system schema), we also introduce the Momentum Diagrams (IF Charts). We hold off on discussing collsions in great detail until after impulses are further studied with unit 5.

The fourth unit, Balanced Forces Particle Model (BFPM), then begins to bring in the concept of forces as the rate of swapping momentum. Here we introduce the major contact forces: normal, tension, friction (name not equation) and the non-contact gravitational force. We also begin using force diagrams to determine if the forces are balanced or not. We stress one way of understanding Newton’s 1st Law as “Balanced Forces -> no acceleration, Unbalanced Forces -> acceleration.”

In the fifth unit, Unbalanced Forces Particle Model (UFPM), we now get into Newton’s 2nd Law in two ways. One the classic: $a=\frac{F_{net}}{m}$

And two, we build the parallel between kinematics and Newton’s Laws. In kinematics, the slope of a position-time graph gives velocity-time, the slope of velocity-time gives the acceleration-time. Finding the area allows us to go the other way. The same is then true of momentum and forces. The slope of a momentum-time graph gives Force vs. time, while the area under a Force vs. time graph give the change in momentum (impulse). For those students going on to calculus based physics, this helps lay the ground work. For the rest, it shows a nice connection between these different models. With this new information, we can now add a Force vs. time graph into the momentum graphs and make “IFF” graphs. Other features of the unit are the building of the equation for friction in relation to the normal force, and the independence of components by looking at 2D projectile motion problems.

We then wrap up the first semester with our 6th unit, Energy Transfer Model (ETM). After building the concept of energy storage through Energy Diagrams (LOL Diagrams). We discover that Energy storage is a “cheat” to help us solve more complex problems, since it is a second conserved quantity. We come back to collisions and find that, in elastic collisions, we can now build a second conservation equation: 1. momentum (IF charts) and, 2. energy (LOL diagrams).

As a review of the first semester, the students will then have to build a paper car that will hold an egg inside. They will have two tests: 1) a speed test to see who has the fastest car and, 2) a crash test to see who has the safest car. During the design, they must make use of all the models we have built this semester.

To start the second semester, we begin studying the Central Force Particle Model (CFPM), or what most people would call uniform circular motion. In this unit we also add in building the concepts of Newton’s Universal Gravitation and satellite motion.

In unit 8 we now move onto full rotational motion, the Rotating Bodies Model (RBM).  To be honest, I may try to split this up into two units, as it’s got a lot of stuff going on here. In short, within this unit we retrace units 1-6, but in the rotating or polar frame of reference. We begin with rotational kinematics ( $\theta$  vs. t, $\omega$  vs. t, and $\alpha$ vs. t). Afterwords, we build in dynamics with angular momentum, torque, and rotational energy storage.

In unit 9, we move on to harmonic motion with the Oscillating Particle Model (OPM). Overall, we stay pretty true to the model materials here. We start with looking at a bouncing mass hanging by a spring. We later bring in pendulum motion.

In unit 10, we then move on to the Mechanical Wave Model (MWM) in which we build a mental model of coupled oscillators. From what I can tell AP-1 only focuses on one dimensional waves, so we looked at boundary effects: reflection (open/fixed) and refraction. We also build in wave superposition. We begin looking at sound waves and doppler shifts as further examples of waves. At least so far, I don’t build in diffraction through “narrow” slits or 2D interference patterns.

In the last unit, we then look at circuits in what I call the Charge Flow Model (CFM). We begin by looking at sticky tape activities to introduce the electric force and electric energy. During that discussion we bring in the concept of gravitational potential ( $gh$), to help understand the concept of electric potential ( $V$). From there, we have them build simple circuits with lightbulbs, then move onto simple circuits with fixed resistors while measuring the current (flowrate of charge). We eventually get to adding multiple resistors in series and in parallel and try to create a model that explains how the resistors add in these two different ways.

To review the entire year, we then do a video analysis project in which the students must analyze movie, tv, or internet videos and determine how feasible those scenes actually are. Here is an example from which I got my idea: