Chickens in a truck?

Question

Okay, here's the situation: a large truck carrying chickens is passing through a weighing station. As the truck passes over the meter, the chickens all suddenly jump up and start flying around. Assuming that they have plenty of room to move about and that the truck is sealed tight, would the meter read more or less than the truck's real weight, or would it read the correct value?

I heard this one a while ago but never came up with a satisfactory answer.

Assume the chickens can fly unimpeded for the (short) duration of the weighing. If you can't deal with that, they can be thousands of hummingbirds or something

Answer 1

This sounds like a grade 11 Physics trick question

Newtons Third Law For every action there is an equal or opposite reaction

Those chickens flying around the truck are exerting an upward force in order to resist their downward gravitational force.

The uplift that will allow them to fly or even jump will create a reaction in the truck bed that will be at least equal to the weight of the chickens them selves.

This reaction is created by Air pressure from the chicken's wings, slamming into the truck bed, this doesnt sound like much but if the truck is selaed then the air pressure has no path to escape but downward through the trucks tires and unto the scale

To all those people who refused to answer this question due to the impossiblity of the scenario can go to hell for being smart alecs, try writing that answer on a test i am sure your grade 11 physics teacher would not have been impressed

Answer 2

Well, for one thing, the question is flawed because there is no way any chicken will fly around long enough to weigh the truck, let alone all of them. Chickens can't fly very well.

But to answer the question assuming chickens can fly. I think it would still register some of the chickens weight since the downward force of the chickens wing against the air will slam into the bed of the truck. I don't know how much, but I'd think the weight would not stabilize and jump all over the place if there were hundreds or thousands of chickens flying around in there. Also, they'd poop a lot and that poop weight would register.

Answer 3

let's change the chickens into ducks.
the weight would stay the same, unless the ducks all glided while the truck was being weighed. this is because they are creating low pressure on top of their wings to stay aloft, not pushing air down against the truck.

Answer 4

well, if no chickens were touching the bottom of the truck, then the truck should read the correct value. If a chicken was fully touching the bottom of a truck, then it should weigh more, as insignificant as it may be.

Answer 5

Would not measure the weight of the chickens but would the true weight of the truck

Answer 6

any chicken that was in the air would not be counted in the weight.
But I say do an experiment! Get a truck and some chickens and find out for sure :)

Answer 7

If the truck is sealed tight then the weight would be the same because they are still pushing down on the air to remain in flight. thought youd get me that one huh.

Answer 8

chickens don't have much room to move at all in those trucks. moreover, chickens aren't capable of flight for extended periods of time, and can't get airborne without substantial running room, so the situation you suppose is an impossible one.