Riddle

no collapse - i have 3 reasons

1) assuming the truck burns fuel like crazy, it hopefully burned enough fuel since getting on the bridge to offset the weight of a [hopefully light] bird.

2) the truck weighs 14000 lbs and but had to have been driven half way with a driver (lets assume who weighs 180 lbs) so obviously it can support more weight than the 14000 lbs it has been rated for, so one extra bird wont make a difference

3) the bridge can support 14000 pounds, which is two significant figures so it can support from 13500. to 14499.999... lbs. If the truck is exactly 14000. lbs then there is up to almost 500 lbs of possible leeway so one bird wont make a difference

In addition to thoh's great answers, I think I'll add something rather... silly.

I think I saw something on Mythbusters about how birds were supposed to DECREASE the weight of a vehicle?

Maybe not

no bridge has an exact load bearing threshhold, something as small as a bird is an insignificant push compared to what atmospheric pressure can force on a bridge.

lol, I must have watched that one too. But I think they were getting at the idea that if a bird inside a car were not resting, it would not be applying its inert weight on the vehicle. I can't remember how that episode turned out though?

A bird flying inside a vehicle is still contributing to the vehicle's overall weight. If the bird is resting then its weight is applied directly to the floor. If the bird is flying then its weight is behing applied to the air, which is then applied to the floor.

BTW: I agree with the answer regarding the truck burning fuel.

The bridge crumbles. The bird takes off, and no one is able to figure out what happens. As a result the driver of the truck is jailed for driving with too much weight on his car :wink: