Trains, planes, and teaching 1D motion, part 2

(There were never any planes.  I was not inclined. ;)

What would it look like 
to have students analyze 
a traffic citation from a 
speed monitoring system?

1. Distribute photocopies of an actual citation.  (I concealed the identity of the recipient and the officer. Don't forget the plates.  If you've not received a citation yourself, I strongly recommend you solicit your friends & colleagues for, er... data.  Here in Baltimore, you can go online and get two amazingly sharp color photos and a video for your $40.)
2. Pose the question:  Was this ticket fair?
3. Students will start asking questions; have rulers at the ready.  You might want to know the make of the car (I Googled the length) or the width of the crosswalk for scale.  With a local citation, you could come with that information ahead of time.  (The photos have time-stamps on them.)
4. Get tech-y with it.  Coach students on making one of the images semi-transparent and overlay them.  Logger Pro will some scaling for them, though perspective is an issue.  They can also do Video Analysis.  (Examples of each below.)
5. Once they start digging, ask -- Was the car speeding?  How well do you know?  What assumptions or approximations are you making?  Is your approximation of the car's speed likely high or low?  How do speed monitoring systems work?
6. The charge: You have been called upon as an expert to testify in this case.  Write up a report for the court with the highest degree of integrity in how you present your findings.  Be sure to include explain how you reached your conclusions as well as the limitations of your work.
7. Prepare for Spontaneous Happy Physics Dance when somebody approximates a scale to compensate for perspective...

At the end of this activity, students will:

• Have a deeper understanding of speed
• Get practice with scaling and different representations of motion
• Have an appreciation for using technology to solve problems
• Know that the driver of this car was speeding, anyway
• Feel empowered to use Physics to fight the Man  (I mean this seriously.)*

*This is a sentence I write with Mary Oliver fully in mind and heart.

Trains, planes, and teaching 1D motion

We have speed cameras here in Maryland, and included in the controversy has been some miscalibration of the equipment.  (Here's an example from the Washington Times.)  The article prompted me to send a send a note entitled "Physics and Speed Cameras" to my colleagues, offering to help if anyone thought she'd been wrongly served.  Here's how one wonderfully bright, funny, and articulate colleague replied:

"These are the problems that always confounded me – if two trains are traveling toward each other, and one is going 50 mph and the other 75 mph and the first one leaves Penn Station at noon for Union Station and the other leaves Baltimore for Newark at 1:15, when will they pass each other? This is why I became an English major. The CPA thing was just a terrible aberrant period in my life that I’d just as soon forget about."

I understand.  Many of us do.  (As my grandmother told it, the question was, "What color were the conductor's eyes?)  Dan Meyer @ dy/dan also balks at these impossibly dull, interest-killing train problems.

Next year, I'd love to put a photo speeding ticket in front of my 9th-grade physics students and ask, "Was this ticket fair?"  The People Will Want to Know.

Any volunteers?

I love Jonathon Rosen's work

for Mother Jones article
Artist's site