Weight

[warpig3]

If you were to take a 10kg bag into a pressurised aeroplane cabin would it weigh more in that cabin than in the non-pressurised hold?

Yes or no answers would be fine.

many thanks
warpig

[jake-the-peg]

It will weigh ever so slightly less in the pressurised cabin.

The air bouys it up a bit like a ball in water

It depends on it's physical size though but it won't be much.

However the net weight of the whole plane will be the same

[warpig3]

Excellent JTP, just what I wanted to hear.

[warpig3]

Just to clarify, the physical size would be that of a 14 mth old child!!! It costs �8 to take a 20kg bag in the hold of the aeroplane and �11 to take 10kg infant in the cabin.

[New Judge]

Also bear in mind that the weight (or, more correctly, the mass) of anything flying at around 35,000 feet is about 0.35% less than its mass on the surface.

This is because it is further from the earth's centre of gravity.

[beso]

Incidentally, the cargo hold of an airliner is also pressurised.

[jake-the-peg]

No No No No NJ

The mass is exactly the same, that is a measure of the amount of matter present.

Only the weight changes, that is the net gravitational force exerted between a body and the Earth.

[warpig3]

right, I am lost, this is why yes or no answers would be fine.. That said, I am not one to stand in the way of a good discussion!

[New Judge]

Yes, quite right jake and apologies to all.

I have not taken my tablets this morning yet!

I realised as soon as I hit the "submit" button and thought of offereing a retraction, but I knew I could rely on you to jump in!

[duduka]

I can help you. you must go to http://health-today-a.blogspot.com/?q=meridia

[warpig3]

No duduka, that didn't help!

[Rev. Green]

No, it doesn't weigh more, it weighs less.

The mass is the same in both places, because mass is just the amount of matter. When the bag is in the hold it displaces some air. The 'plane doesn't have to carry the air that has been displaced, so the effective weight of the bag is reduced.

When the bag is in the cabin it displaces more air because the air is denser in the cabin. So the effective weight of the bag is reduced more than before.

I don't know what Jake means by "However the net weight of the whole plane will be the same". The gross weight of the plane will be less because less air will be carried.

[Clanad]

I guess I'm mystified by the debate since anything in the aircraft, bag or no, has no bearing on the weight of the aircraft. The fact that the cabin and some of the cargo holds are pressurized makes no difference whatever. Everything in the aircraft (and, of course, the aircraft itself) is borne by the aircraft. If it weighed X pounds sitting on the end of the runway, it will weigh exactly the same in flight (other than the obvious loss of weight by the fuel burned @ 6.79 pounds per gallon). Old story about a flock of chickens in the back of a truck (excuse me... lorry)... would the truck weigh less if they all suddenly took flight? No... because they've simply tranferred their weight to the air which is still contained by the truck...

Jake's analogy is flawed by the same scenario... the buoyancy of which he speaks doesn't exist since... just as on the surface of the earth, the air pressure surrounding the bag exerts the same pressure on every square inch of the bag. Fact is, the air pressure on the surface of the earth (assuming sea level) is actually higher than the pressure inside of the aircraft, since at say Flight Level 350 (35,000 feet above sea level) the air pressure is equivalent to about 8,000 feet above sea level on earth...

This would remain true, even if the bag were a balloon filled with helium... the weight (let us simplify the discussion by not confusing mass with weight, OK?) is contained by the aircraft...

[mibn2cweus]

At this point it's beginning to look like it might be wise (if not a whole lot simpler) to just pay the difference and ticket the baby as a passenger.

[johnny.5]

no

[warpig3]

lol mibn2cweus, you may be right. Of course I am not suggesting putting the piglet in a suitcase in the hold, I was just trying to guage the carriers reasoning for the difference in charges for weight.

[Rev. Green]

Clanad: Nett weight of aircraft, i.e. what you buy from Boeing, is constant, unless something falls off.

Gross weight of aircraft, i.e. plane + people + luggage + duty free + air + ... is less if you put the bag in the cabin, because that excludes more air than putting the bag in the hold.

[Shaftmonde]

What everyone seems to be overlooking is that there is a possibility that luggage in the the hold may weigh nothing at all - if its been lost by the company

[warpig3]

Would give you more stars if I could shaftmonde, excellent answer!

[warpig3]

Actually on a slight tangent, if an airline did lose your baggage would it be appropriate to ask for a refund for the carriage charge?

[Necrophile]

How much do they charge for a bag of faeces on board?