On 01/23/2011 10:04 PM, Harry Veeder wrote: > The truck would be lighter while it crosses the bridge if the chickens > could jump so high that they remain in the air until the truck is over > the bridge. Assuming the chickens have super thighs and aren't boxed > in. ;-)
But then the chickens have actually jumped clean over the river (or whatever) while the truck drove over the bridge ... seems kind of like it's cheating. :-) You can also "cheat the dealer" if the chickens are in wire mesh cages, with mesh bottoms, an open (or latticework) bottom on the truck, and the bridge has an open metal honeycomb bed (like Pont Victoria in Montreal -- it's a little freaky to look down while you're driving over it, and see the river an awfully long way below). Since the momentum transfer from the flying chickens to the truck is through the air, if the air's allowed to flow freely out the bottom of the truck and through the bridge surface without interacting with anything, you don't "pay" for the weight of the chickens. > > Harry > > > > > > On Sun, Jan 23, 2011 at 3:36 AM, John Berry <aethe...@gmail.com > <mailto:aethe...@gmail.com>> wrote: > > Of course, in practice the results can sometimes indicate that > momentum isn't conserved. > > This example is in principle not dissimilar to some inertial > propulsion concepts and there is evidence that some may work. > > > On Sun, Jan 23, 2011 at 3:19 PM, Stephen A. Lawrence > <sa...@pobox.com <mailto:sa...@pobox.com>> wrote: > > > > And when a truck full of chickens with 3 ton gross weight > is about to > drive over a bridge rated at 2 tons, it doesn't do the > driver any good > at all to bang on the side of the truck. The chickens all > fly up into > the air inside the truck, but none the less, it still > requires 3 tons of > upward force on the wheels to support the truck and > chickens. ('Course, > if he's got a ton of chickens on board, chances are > they're too fat to > fly, anyway.) > > > >
