Buy that special someone an AP Physics prep book, now with 180 five-minute quizzes aligned with the exam: 5 Steps to a 5 AP Physics 1

Visit Burrito Girl's handmade ceramics shop, The Muddy Rabbit: Yarn bowls, tea sets, dinner ware...

22 August 2009

Mailbag: Dead Rats


I’m back from Yosemite, where I probably COULD have posted to this blog if I had wanted to – I saw not one but numerous people talking on cell phones while they hiked the trails. Nevertheless, I went somewhat old school, and stayed out of touch. I’ll be back to Woodberry on Tuesday, and frequent posts should begin again as the start of school approaches for me.

For now, chew on this question, asked by a participant in one of my AP Summer Institutes:

“I was re-reading some of the materials you shared, particularly your homework submission guidelines. There is one thing I don't get: What is a dead rat?”

-- Samuel Holiday, Pinson, Alabama

I learned the term a decade ago from Arkansas professor and AP reader Gay Stewart, though it wasn’t her invention, I don’t think.

Say you find a dead rat in a pickle barrel you're selling. Well, if you remove the dead rat before the customer sees it, you can still sell the pickle barrel, though possibly at a discount. If you don’t remove the dead rat, you're in big trouble.

In physics, a "dead rat" is a bloody ridiculous answer: a commercial airplane that has a mass of 10^2 kg... a car moving 10,000 m/s... not just an incorrect answer, but one that could and should be ruled out based on any kind of physical sense.

An unidentified dead rat causes a student big trouble to the tune of an enormous loss of points, regardless of the reason for the error. But if that student points out the dead rat and how he knows an answer is a dead rat, then he'll lose very little credit.

GCJ

No comments:

Post a Comment