Does a sealed lorry containing budgies weigh less if they are flying than when sitting on perches?

Question

Its an old conundrum, and one that I feel has never been answered properly.

Answer 1

the only way a bird can fly in the first place is because their wings are pushing down on the air.
the force of the air pressure downward equals their weight.
the total weight will be the same!
it's called basis conservation of energy in a closed system

Answer 2

I agree with the line that they all weigh the same, but if the whole lorry was placed stationary on a big scale, it would show heavier when the birds were sitting. When they are flying they do use their wings to push down air with the same force required to keep them up, but due to friction in the air, not all that downward force is transfered perfectly onto the lorry platform. Therefore, the flying ones apply less downforce to the lorry, despite the the law of conservation of energy, because some of the energy is turned into heat and sound by friction in the air.

Answer 3

Oh god, I hate these questions, its like that old myth that if you are in a falling lift, you should jump just before you hit the bottom, then you won't be injured.

I would say, if you are talking about physically raising the lorry and placing it stationary on a big set of scales, it would weight exactly the same as if the budgies were sitting down.

But I would have thought, in terms of pressure applyed on the road, that it would be less if the budgies were flying.

Argh, I don't know!!!!!

Answer 4

Surely not!!
you are talking about two different masses, mass of the lorry and mass of its contents.
Since P=mg, P being the weight force, m - mass, and g - gravitational acceleration, weight will be proportional of the mass.

the mass of lorry in either case remains the same

but in case when birdies are sitting on perches, they will apply pressure to the lorry, thus their mass will add to the lorry's mass. You'll just be counting their weight combined, P = ( m1 + m2 )g

however, if you manage to launch this lorry into open space, that is, place it in vacuum, their mass will equal to m1+m2, but they will effectively weigh nothing, since g will be zero and P will be zero. I think--------

actually physics is the only school subject i've never been good at

Answer 5

the lorry weighs exactly the same, and so will the contents, but what it'll show on a scale depends on how many budgies will be sitting down - a scale won't be able to weigh the flying ones... ;)

Answer 6

If the cage is closed the respond is straightforward. the burden is an identical. The thrust of the wings strikes air down and the thrust of this air on the floor precisely fits the raise. subsequently the burden on the floor is an identical with birds flying as though transmitted in the time of the perches. If the cage is open this is greater complicated because of the fact there is the aptitude to create a circulate of air from outdoors. And a circulate of air ought to create raise. Or it ought to create added downward tension. It relies upon on the form of the openings and the air circulate they convey. to furnish an analogy, the airflow created by making use of a helicopter supplies it raise. opposite an identical result and the airflwo created by making use of a formulation a million vehicle holds it on the floor.

Answer 7

The weight is the same if they are holding constant altitude in the lorry. For every action, etc. etc.

If they are climbing, the lorry will be heavier, since they are applying extra lift to their wings beyond their weight. If descending, the lorry is lighter.

Answer 8

it weighs the same, when the budgies are flying they push the air creating a downforce equal to their weight on the floor of the lorry.

Answer 9

I suppose it would weigh the same otherwise you could put a helicopter in an enclosed container bolt it down to the bottom and it would fly with no visible mean of support.

Answer 10

Yes it does. When they are perched they weigh a little, but when flying they weigh less than the air.