mythbusters: flying birds make truck lighter?

[josephus]

I was just watching the episode of mythbusters where they test the myth that claims that if you have a bunch of pigeons inside a truck, the truck will become lighter if all the birds are flying.

from my understanding of the physic, if the birds are flyings the overall weight of the truck will not change since the birds are supported by the air, which create a downward force on the truck equal to the weight of the birds.

my question is for a slightly different setup. in this scenario we have a truck that carries a bunch of tennis balls. now if i throw all the tennis balls up, does the weight of the truck go down?

i suspect the answer is yes, but am not sure.

[jfinkels]

I was just watching the episode of mythbusters where they test the myth that claims that if you have a bunch of pigeons inside a truck, the truck will become lighter if all the birds are flying.

from my understanding of the physic, if the birds are flyings the overall weight of the truck will not change since the birds are supported by the air, which create a downward force on the truck equal to the weight of the birds.

my question is for a slightly different setup. in this scenario we have a truck that carries a bunch of tennis balls. now if i throw all the tennis balls up, does the weight of the truck go down?

i suspect the answer is yes, but am not sure.

The weight (i.e. the downward force of the truck represented by the mass of the truck times the acceleration due to gravity) of the truck is constant. The weight of the truck PLUS the balls will change if you change the number of balls that are carried on the truck. This is because you would be changing the total mass of the system.

[use a name]

The moment you throw a ball in the air, you are execising a slightly bigger force on the truck for a moment. After that, the weight of the truck is less indeed, until the balls land in the truck again.

[prizrak]

The moment you throw a ball in the air, you are execising a slightly bigger force on the truck for a moment. After that, the weight of the truck is less indeed, until the balls land in the truck again.

What he said :)