Physics Question?

Question

A truck driver is transporting a fully in-closed trailer full of birds. He knows he is over weight so he pulls over to the side of the road before the scale and bangs on the trailer, causing the birds to go into flight. He then drives over the scales. Did the weight of the trailer change?

Answer 1

Yes, simply because of this: If you hop on a scale, then jump up, your weight is gonna drop.

Answer 2

No. Your key condition is that the trailer is "fully enclosed".
Thus, when the birds "fly" off the floor of the truck, they cause
an equal amount of air pressure (force) down, resulting in
a net weight change of zero. Weight of trailer is the same.

Now, if the container with the birds were open, and the birds flapped up, that would be different. Air pressure (wind, etc...) from the outside would change the whole equation.

Good question.

Answer 3

Think about Newton's First Law. For every action, there is an equal and opposite reaction. While the birds are in flight, they have to send air downward (force) to keep aloft. So as they are in flight and not moving up or down, the weight will stay the same. If they are moving up, the force (weight) will increase. If they are gliding, moving down, the weight is less.

Also think about outside forces. Since there are no outside force, the weight stays the same.

Answer 4

No - since it is enclosed (and air tight I assume) the wings of the bird are pushing down on the air which is supporting them. The air is pushing down on the truck.

Answer 5

No. The container and it's contents get fully weighed no matter how they are dispersed throughout the container.

Answer 6

yes it gets lighter