Lateral Thinking Questions

===============
ANSWER: L.T.Q. #29  !
===============
Date: Wed, 17 Jan 1996 13:21:00

Sorry this answer is coming late, but I forgot to send it out before I went on nights last week.

Here is this week's question:

A truck was loaded with a flock of birds, but it was too heavy to cross the bridge. If the driver spooks the birds so that they are constantly flying about the back of the truck will this make the truck lighter and allow it to cross the bridge?

ANSWER:

No, since the total mass (combined air and birds) in the back of the truck does not change. If this doesn't make sense, think of this analogy. If you have a beaker of oil with water on top, does its total mass change if you stir the oil and water together?

John got the wrong answer, but gets bonus marks and a chance to swab the poop deck for saying: "Yes, unless by spooking the birds too much, he scares the crap out of them and the weight of the crap is too much; this is especially true of Canada geese who are known to defecate every minute."

Craig gets philosophical points: "I don't think so.... ok let's say for a moment that the truck had some kind of wire mesh sides or something so that the weight would actually be less (in a box, the weight would be the same regardless of what the birds are doing because the mass is unchanged) anyway, the mass density of an enclosed space with a bunch of birds flying around would be so low as to not have a significant enough contribution to the overall mass of the of the truck. Or in other words, the birds weigh practically zero compared to the truck and would not make be sufficient to affect a make or break situation. Or this that answer too Cartesian?"

Ok. So, given that the truck is going to fall into the ravine when the bridge gives way, will the birds be able to survive the crash by being airborne at the time of impact? (If you don't think falling into a ravine will spook birds, just try moving quickly across my living room and see what happens!)

Return to Questions.

This web page is maintained by Mike Jourard using HTML Notepad from cranial software.
Last modified on January 17, 1996. Converted to dot-com web site on May 22, 2000. Copyright © 1996,2000 by Badinage Publications. All rights reserved.