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A physics question for Tom and Ray

Car Talk

Dear Tom and Ray:

I was involved in a car accident. My car was thrown 83 feet. The guy who hit me was driving a 2002 Thunderbird, weighing 3,775 pounds. My car was a 2006 Toyota Matrix, weighing 2,679 pounds. Is there any way that I can calculate how fast his car was going at the point of impact? I was turning left, and the guy smashed into my passenger side as I crossed his lane. I would say the angle at which he hit me was about 110 degrees, since I wasn’t quite at 90 degrees to him yet. I was just starting to turn, so I was going no more than 5 mph. I ended up 83 feet away. There were no tire tracks at the point of impact, so my car must have gone airborne! This seems like a physics problem, and I have contacted some physics students, but they are students and are not interested. I think it should be possible to calculate it, but I don’t know physics. Please help! My car was totaled. The other guy claims he was going 35 mph, but given how far my car went, that just doesn’t make sense. — Cathy

TOM: Well, we happen to have our very own physicist on staff, Cathy. Wolfgang Reukner, who moonlights teaching physics at Harvard, handles just these sorts of questions for us.

RAY: Along with questions about how much glue you need to keep your rearview mirror from falling off the inside of the windshield.

TOM: So we sent Wolfgang all of the salient data, and he scribbled it all down, mumbled stuff about mass, distance, force, angstroms, Bohr models, antimatter, absolute motion and something about remembering to pick up milk on the way home, and then he told us how fast the guy who hit you was traveling.

RAY: Thirty-five mph. Maybe even slower.

TOM: Now, he cautions us that that’s an estimate. He doesn’t know whether your car skidded the entire 83 feet, or rolled some of the distance. He did not take into account any curbs you had to cross over or how many park benches you took out along the way. So he says that if you’re planning to go to court, he would appreciate it if you would leave him out of it!

RAY: There are forensic accident physicists who do this for a living and do sophisticated computer modeling to really narrow down the speed of each vehicle.

TOM: But if you’re just interested in knowing if the other guy is being truthful, it sounds like he might be; a speed of 35 mph is consistent with the rest of the information.

RAY: But as you now know, being hit by another car that’s going 35 mph creates a very violent collision. And we hope all of our readers will keep that in mind before checking their phones for a text message.

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If it ain’t broke, you won’t have to fix it! Order Tom and Ray’s pamphlet “Ten Ways You May Be Ruining Your Car Without Even Knowing It!” Send $4.75 (check or money order) to Ruin, P.O. Box 536475, Orlando, FL 32853-6475.

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Get more Click and Clack in their new book, “Ask Click and Clack: Answers from Car Talk.” Got a question about cars? Write to Click and Clack in care of this newspaper, or email them by visiting the Car Talk website at www.cartalk.com.

(c) 2014 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.



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