It doesn't matter if the tyre has air in it, because the system is roughly in equilibrium, since the tyre isn't supporting any pressure, therefore you could weigh it pretty much ignoring the remaining air...
Of course there is a diffference between liquids and gases. Liquids run into the streams and gases float. AFAIC gases don't weigh anything. When they talk about air pressure, they're referring to the emotional tension of never knowing where one's next breath will come from.
Of course they weigh something.
Some are denser than air and sink. For example CO2. Remember that village smothered in Africa. That was CO2 rising from a lake then moving along the ground.
Some are lighter than air and rise. Helium is an everyday example.
Some like Nitrogen and Oxygen are about the same as the mixture of gases we call air and just disperse. If you weighed them on an everyday scale the scale would say zero, but they have mass and are attracted to the Earth by gravity.
Next question:
Will a closed box with a bunch of canaries in it weigh less if the canaries are flying around than if they are walking around on the inside bottom.
Jeff
Even better question, did mm just wake up from a year long nap? LOL
Canary question is interesting. My answer is the box would weigh the same, because gravity is still acting on both the box and the canaries. The upward force against the canaries wings which is keeping the canaries in the air causes an equal an opposite force against the air, which ultimately is transfered through the air and to the bottom of the box, resulting in the force which we call weight.
Your correct of course, but the simpler answer is just that the mass of the box and all the stuff inside it stays the same, so its "weight" must too.
Fot thse who don't already know this one, which way does a kid's free floating helium balloon moored on a string inside a schoolbus move when the bus decelerates, and why?
Jeff
Relative to the bus, or to the ground :)
nate
You noticed that! Very good.
Jeff Wisnia wrote: have mass and are attracted to the Earth
Another question involving "sublimation."
There is only one common substance that transforms directly from a solid to a gas without passing through a liquid phase first. What is it?
(answer below)
A taco.
The direction of acceleration. Because it's lighter than the air around it.
There are lots, but snow comes to mind. Dry ice?
Ever barfed one up?
If the box has been closed long enough, the canaries will all be lying on the bottom of the box, dead of suffocation.
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