Big Rigs

Dec 07, 2009

RAY: This was from my traveling salesman series and it was sent in by Tom Greene. Here we go:

I work as a traveling salesman and I drive my own car on our busy highways and byways in an effort to call on as many clients as I possibly can on any given day. Now when I'm on the highway I usually set my cruise control for a few miles per hour above the posted speed limit and whenever I'm on a highway whether it's a two or three or more lanes, I find myself traveling for the most part in the left lane.

From time to time I'll come upon a group of big rigs, you know eighteen-wheelers, semis, those big trucks and they're all traveling one behind the other. As I close the gap between them and me, I usually don't even have to speed up to pass the whole lot of them. Don't forget, I'm already exceeding the speed limit. But it seems that quite often one of the drivers in the middle of the pack, say, decides that he or she wants to go faster than the leader. Maybe the driver has got an urgent need for a haircut or something. And as soon as that impatient driver pulls left to pass, he slows down! That's right, he slows down.

Now it appears to me, that the trucker sees me closing in on him and decides, 'I'll teach this jerk a lesson. I'll pull out and slow down, so Mr. Speedy will have to slam on his brakes.'

What's going on?
RAY: Here's the answer. What these trucks are doing is something called drafting. The trucker that's in front is actually encountering most of the wind resistance. And the other trucks behind him are actually being drafted or pulled along by him.

TOM: Sure.

RAY: And when they do this, those trucks actually get better mileage, and they can go farther and faster on less fuel. And interestingly the guy in front is also getting better mileage, because they're pushing him along, believe it or not.

TOM: Oh.

RAY: But when one of them pulls out to pass he's no longer being pulled along by his buddies, and in fact he is now encountering all that wind resistance, and even though he doesn't want to, he slows down. He can't help it. So it wasn't for spite, it's just the way it works. Do we have a winner?

TOM: Yah. Our winner this week is Dorothy Smith from Bethany, West Virginia. And for having her answer selected at random from among all the correct answers that we got, Dorothy's going to get a $26 gift certificate to the Shameless Commerce Division at, with which she can get a boxed set of 'Disrespectful Music' CDs.

RAY: Congratulations, Dorothy!

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