Originally posted by LemonJello
Supposing that the bridge's capacity and the "exact weight" of the truck are equal at the point when the truck first enters the bridge; and then the truck makes it half-way across before the bird lands; then I guess the answer should depend on the comparative weight of the bird and the fuel expended while the truck is on the bridge. Hopefully, either the truck is a fuel guzzler; or it's not a big bird; or both.
Nice one lemon.
one US gallon of diesel weighs 7.15 pounds which is 3.3kg
A large truck does between 10 and 5mpg, so in 1/2 a mile of bridge it will burn between 1/20th and 1/10th of a gallon of diesel, i.e. between 165 and 330 grams
So, how much does the bird weigh?
A sparrow weighs between 24 and 32 grams
A pigeon weighs between 280 and 450 grams
So, the bridge will stay up if it is a little bird, but is likely to fall down if it is a biggish bird.
If he stopped because he got a flat though, he has a little more leeway, I can't find the dimensions a a typical large-truck tire (anybody know?) but I'm guessing that truck tires might hold 100g of air, meaning that the bridge is quite likely to survive if the truck is also of low efficiency.