Tag Archives: lab

Video Analysis of a Bouncing Ball


Nothing earth-shattering here. I just wanted to share the activity we worked on today, which was an introduction to quantitative energy conservation by doing a video analysis of a bouncing ball. (Up until now, we were only doing qualitative energy pie charts.) Here are the handouts and the video:

The graphs from the analysis are just beautiful:

HeightTime VelocityTIme EnergyTime

Lots to talk about in those graphs!

Feel free to edit and reuse the handouts as you see fit. They’re not perfect, but I figure it’s better to share them than having them collect dust on my flash drive.

PS: I’ll sheepishly admit that I don’t do the whole suite of paradigm labs in the Modeling unit to mathematically derive the energy equations from experiments. But we do some simple qualitative demos/experiments to discover what variables would be in those energy equations. We start by talking about how the further a rubber band is stretched, the more energy it stores. Then we launch carts into a rubber band “bumper” (i.e., big rubber bands from Staples and two C-clamps) to qualitatively see the energy stored.

In doing so, we see that the cart’s kinetic energy depends on its speed and its mass. (Or is it weight? What would happen if we repeated the experiment on the moon?)

For gravitational energy, we can repeat the experiment, but have carts rolling down an incline. Or use the rubber band to launch the cart up the incline. I’ve also dropped balls into sand and looked at the depth to which they get buried. Either way, we see that gravitational energy depends on height and weight. (Or is it simply mass? What would happen on the moon?)

For elastic energy, we already know it depends on the distance the rubber band is stretched. Then, we can swap out the rubber band in the bumper with a stiffer/looser one to see the effects of the spring constant on energy stored.

Then, after we predict what the energy equations might look like, I just give them the actual energy equations, or have them look them up. (Gasp! See Schwartz’s A Time for Telling, aka Preparation for Future Learning.)

So, modelers, what am I missing by not doing the full-blown energy paradigm labs? How do you introduce the quantitative energy equations?

My TEDxNYED Session: Learning Science by Doing Science

Many thanks to the TEDxNYED 2012 crew, especially True Life Media, Basil Kolani, Karen Blumberg, and Matthew Moran for an awesome event. Be sure to check out the rest of the TEDxNYED 2012 talks.

Learn more about Modeling Instruction in Science.

Physics of Angry Birds Lesson on CUNY-TV

Many thanks to Ernabel Demillo and the crew of Science and U!

You can read more about how we use Angry Birds in class here:
Angry Birds in the Physics Classroom

Physics Teaching 2.Uh-Oh

My first talk! Given at the STANYS 2011 Physics Breakfast on November 8th, 2011 in Rochester, New York

Links to resources mentioned in the talk:

A huge thank you to Gene Gordon for inviting me to speak at the breakfast. It was great to share my passions and meet my virtual colleagues face-to-face!

I’d love any feedback you have, positive and negative. Thanks!

Khan vs. Karplus: Elevator Edition

Exhibit A: Sal Khan on elevators

Exhibit B: My students on elevators
Framed around the Karplus learning cycle (Exploration, Invention, and Application) my students construct the conceptual and mathematical models themselves.

1. Exploration Phase:

2. Invention Phase: 

  • Draw a motion diagram for the object attached to the scale when the scale is stationary, then being pulled up and then stops.
  • Draw a force diagram for the object attached to the scale when the scale is stationary, then being pulled up and then stops. Decide whether the force diagram is consistent with the motion diagram. How is the force diagram related ot the reading of the scale?
  • Use the force diagram and the idea under test to make a prediction of the relative readings of the scale.
  • Observe the experiment and reconcile the outcome with your prediction.

(Video and questions for this phase taken from Eugenia Etkina’s awesome site Physics Teaching Technology Resource which has many more video experiments.)

3. Application Phase:

Instead of showing our students a better lecture, let’s get them doing something better than lecture.

UPDATE: Welcome New York Times readers! Other recommended posts:

Angry Birds in the Physics Classroom

I recently blogged that you can now play Angry Birds in your web browser. This opens up all sorts of video analysis possibilities for physics lessons and assessment. Students can easily make their own videos or you can pre-record your own. Videos can be recorded using Jing, Screencast-O-Matic, or Camtasia Studio. Analysis can be done in Logger Pro or Tracker.

Here are some possible investigations to carry out (shared by Michael Magnuson on the WNYPTA email list):

1. Make a reasonable estimate for the size of an angry bird, and determine the value of g in Angry Bird World. Why would the game designer want to have g be different than 9.8 m/s²?   Download Angry Birds video.

2. Does the blue angry bird conserve momentum during its split into three?  Download Red and Blue Birds video.

3. Does the white bird conserve momentum when it drops its bomb? Why would the game designer want the white bird to drop its bomb the way that it does?  Download White Bird video.

4. Describe in detail how the yellow bird changes velocity.  You will need to analyze more than one flight path to answer this question.  Download Yellow Birds video.

5. Shoot an angry bird so that it bounces off one of the blocks. Determine the coefficient of restitution and the mass of the angry bird.  Download Red Birds and Falling Block video.

You can download each video using the links above or get them all here.

Other posts with ideas about how to use Angry Birds in physics class:

How have you used (or will use) Angry Birds in the classroom?

UPDATE 12-28-2011: Our class has been featured on CUNY-TV’s “Science and U!” Jump to 10:25 in the video below:

Increasing Engagement in Science

As part of a session on innovative practices in science at TeachMeet New Jersey 2011, I gave a presentation entitled “Tips, Tools, and Techniques for Increasing Engagement in Science”

I have posted that presentation, complete with speaker’s notes and plenty of links to further information, here: http://bit.ly/EngageSci

Any feedback you have would be greatly appreciated! (e.g., is there a bigger theme I am missing, etc.) Thanks! J3BC3J3HSY8J