Is a truck full of birds lighter if the birds start flying?

Answer 1

if the birds start flying they are not loading down the truck so common physics would say it wouldnt be so heavy.

Answer 2

As it turns out, the truck is no lighter when the birds fly. First, if it could be lightened this way, you could build an antigravity machine using this principle.

To understand why the truck is no lighter, consider what is keeping the birds aloft. There are many lift mechanisms but all of them produce lift by forcing air downward. By the conservation of momentum, the momentum of the downward air (mass times velocity) equals the weight of the bird over time. The air rushing downward from the bird wings, pushes on the floor of the truck causing a force. This is just like the force you feel in front of a fan.

The momentum of the rushing air being stopped by the truck floor produces a force equal to the weight of the birds.

Answer 3

I'm trying to figure out how you got a truck full of birds. I mean...even if was a small truck, that's still a lot of birds. Who has that many flying birds for sale? I mean, you can get chickens or turkeys, sure...but those don't really fly all that much. You're probably lookin' at parakeets or hawks or something. And how you do you get them all in there? And do you have ANY idea what kind of a mess a truck full of birds would leave in that truck?

No sir, I don't recommend this. Not at all.

Answer 4

Good question, but no the truck would be the same weight. For every action there is an equal and opposite reaction. Whatever force keeps the birds in the air is also acting in the opposite direction and pushing down on the truck.

Answer 5

This is a really interesting question. The answer is no. The birds must force air downward in order to stay up in the air, and that force is equal to their weight even if they are not touching the floor of the truck. An interesting corollary to this is that a helicopter above a large lake will displace, according to Archimede's principle, a volume of water equal to its weight!

Answer 6

If it is a closed area, no - because the air doesnt move away from the truck.

If it is open, then probably not either, because any negative pressure effects would be negated by air flowing into the open area as the truck drives.

Answer 7

Yes, of course!

Answer 8

yes

Answer 9

yea

Answer 10

i would think so