Imagine a plane full of caged birds...?

Question

Would the plane weigh heavier if the birds were on their perches or flying about their cages?

Answer 1

No because even when they are flying they are inside a packed system and there weight is somehow managed by the plane.In the case they are hovering they transfer it via air pressure.

Answer 2

Hi Andrew,

Splendid Q.
Your previous answers stating that the down-force of the birds would equate to their lift factor, and so balance out, are fine & sound, but not taking into account forwards or backwards motion. Another issue ?
Surely a factor, but here's an interesting similar set of circumstances.
A group of us in the back of a C130 Herc , no seats, strap-hanging in the Mid East were asked by the loady sergeant to all leap up on take-off, as the plane was "a bit too heavy to clear the fence at the other end of the strip".
I watched in amusement and amazement as a dozen blokes did so.
Could of put it to music !
Of course we all crashed into the sea as 150 stone of bods arrived back on the floor. (Not).

In terms of pure physics, as the equations go -
F+I2 = F-12 (-1 + the loady)

Heh Ho !
Bob.

Answer 3

On the perches. No weight downwards on plane when flying.

Answer 4

If we want to get technical, the birds fly by pushing down on the air below them. That air then collides with the cage below, which in turn counters what its weight is to keep it in the air. They would weigh the same .

Answer 5

What an excellent question! That's one of the things I love about coming here. Its thought-provoking.

Instinctively I would say on their perches, but the other answers are intriguing.

Answer 6

The plane wighs the same in both cases.

This weight can be found by finding the influence of the gravitational force on the plane:

Fg=(mass of system) * (gravitational constant)
Fg=(mass of birds+mass of plane in kg) * (9.80 newtons per kilogram)


anyone who says different did not pass grade nine physics.

Answer 7

No difference. If the birds are flying, their weight is being imparted to the aircraft by the air currents from their wings.

Answer 8

The plane and its cargo would not change in weight whatever the birds do.

Answer 9

i will anticipate you meant that all of them took off and landed on an identical on the spot. whilst they take off, they might push the airplane down. simply by fact the birds get to the outstanding of their flight direction interior the airplane, they momentarily grow to be weightless and could desire to furnish up flapping their wings for an on the spot. additionally the birds grow to be weightless as they descend to the floor of the airplane. If the birds hover in sustained flight interior the airplane, the airplane will weigh an identical, not simply by mere actuality that they are interior the airplane (until they drift like balloons), yet simply by downwash of the wings pushing on the floor of the airplane. So, speedy precis: Birds take off- airplane feels heavier. Birds attain the outstanding, or descend- airplane feels lighter. Birds in sustained flight- airplane feels an identical. it certainly relies upon on the action of the birds relative to the airplane, not what's right now helping them. it could desire to be the floor, or their perches, or the air, or the flight attendant or in spite of; does not remember.

Answer 10

Try this, Put a cup of water on a set of scales and let them settle, now stick your finger in the water, Interesting eh?

Same sort of thing