Science Questions

Does it weigh less to transport flying birds?

Sun, 28th Nov 2010

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Question

Mike Zinner asked:

I look forward to the podcast each week.† It took me quite a while to catch up to the present shows as I've listened to all of them to date.† I hope the show runs as long as you folks want it to.

My question actually comes from a cartoon panel in a 1940 New Yorker magazine:

If I have a small truck with 500 lbs of birds in the cargo area, and 1/2 of them are in flight at any one momemt, will the weight be less?†

Mike Zinner

Minneapolis, Minnesota (yes it's getting quite cold already) USA

Answer

We answered this with regards transporting birds in aeroplanes...

Dave -   Not for very long.  Basically, birds hold themselves up by pushing air downwards and so, as they push air downwards, they get an equal opposite reaction, they're held upwards.  The problem is that the air is going to keep on moving downwards until it hits something else.  If it were in a plane, it will hit the bottom of the plane and therefore, that air will get slowed down and itíll transfer exactly the same force to the plane.  So for the time it takes for the movement of air to get from the bird to the plane, the plane will weigh less but as soon the air hits the plane, then it will go back to what it weighed before.

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Mike Zinner asked the Naked Scientists: I look forward to the podcast each week.† It took me quite a while to catch up to the present shows as I've listened to all of them to date.† I hope the show runs as long as you folks want it to. † My question actually comes from a cartoon panel in a 1940 New Yorker magazine: If I have a small truck with 500 lbs of birds in the cargo area, and 1/2 of them are in flight at any one momemt, will the weight be less?† † Mike Zinner Minneapolis, Minnesota (yes it's getting quite cold already) USA What do you think? Mike Zinner, Sun, 14th Nov 2010

This would have no affect on the weight of the truck. SteveFish, Sun, 14th Nov 2010

yes, if the the floor of the trailer was made of grates with holes that would allow for the flutterforces to pass thru the floor? CZARCAR, Tue, 30th Nov 2010



I think you'd need to do something similar with the roof too. Geezer, Tue, 30th Nov 2010

Why do people keep asking the same question? Bored chemist, Wed, 1st Dec 2010

I don't think you would have the room for the birds to fly. Get a bigger truck, say a 13.6m artic (semi).

Oooo Ouch! You nitpicking, padantic old git! Don_1, Wed, 1st Dec 2010

the birds ate the fly so the followup was impossible. CZARCAR, Wed, 1st Dec 2010


Because the people whose name appears in black by their post* (rather than as a link to their forum profile) have sent questions to The Naked Scientists radio show by e-mail/twitter/facebook, and thus don't actually know that this is a question that crops up on the forum regularly. Their questions are then posted here by the TNS team (and they're sent a link to the thread.. quite a number of people subsequently register for proper accounts and join the forum by this route).



* Except for the people who've posted on the forum themselves and then for one reason or another chosen to delete their account rosy, Wed, 1st Dec 2010

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