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[kurupetos]

Air pressure is lowest at the top of Mt Everest so if anything that bottle should bloat not crumble.

NB: …but keeping the air inside the bottle at sea level temperature (and thus sea level pressure) to test this would be difficult unless its flown up there with a chopper or something.

As I wrote above, American English is tricky.

[cyprusgrump]

Yes, but pressure always decreases as altitude increases....

Definitely, I didn't claim anything different.

But if the pressure decreases the bottle would expand... not crumble

[cyprusgrump]

If you read it carefully and slowly you will realise that my only reference to vacuum was to explain his speed.

No it wasn't. You referred to sound in a vacuum whilst thinking you could explain sound emanating from his mouth...

... he was travelling so fast because he was in a virtual vacuum where there can be no sound anyway.....

(BTW - continually resorting to how you lost the plot by quoting my "Amazing!" aside above, just reinforces your suffering. )

No, read it all again... It is only you that had difficulty understanding his ability to be heard (in your 'amazing' comment) when he was travelling faster than the speed of sound...

Shortly after, this was posted: -

When did he actually travel faster than the speed of sound, as it is not a constant and depends on air density and temperature?

690mph is considered to be the speed of sound at sea level, I am sure he wasn't going that fast then!

To which I replied: -

You're quite right...

It is a bit of a con really isn't it... he was travelling so fast because he was in a virtual vacuum where there can be no sound anyway....

Concorde used to cruise at 'twice the speed of sound' which was about 1,350mph so they must choose some arbitrary figure...

So you see, when you stop your nasty little habit of obfuscation and miss or partly quoting what other people have said it becomes perfectly clear that what you have been claiming all along is false.

There is simply no reference whatsoever to the sound coming from his mouth in that quote.

[kurupetos]

Yes, but pressure always decreases as altitude increases....

Definitely, I didn't claim anything different.

But if the pressure decreases the bottle would expand... not crumble

That's why I posted the following above...

i have a question for the real physicists.....when driving up a mountain why would an empty plastic water bottle with cap on it crumble?

Because of the density change.

Surely it wouldn't crumble... unless someone sat on it.

Maybe it's a mistake. American English is sometimes tricky.

[bill cobbett]

Yes, but pressure always decreases as altitude increases....

Definitely, I didn't claim anything different.

But if the pressure decreases the bottle would expand... not crumble

Yes... look at the helium balloon that the sky-diver used to get up into near space.

On the ground these balloons are all floppy and look under-inflated but as they rise into thinner and thinner air they expand.

A child's helium-filled balloon will likewise expand to the point they explode at altitude.

[Get Real!]

To cut a long story short, by the time a car drives up a mountain whatever is in that bottle will attain whatever temperature is in its surroundings so I don’t expect anything to happen to it. It’s a very sudden change in temperature that could cause a bloating or the opposite.

[kurupetos]

To cut a long story short, by the time a car drives up a mountain whatever is in that bottle will attain whatever temperature is in its surroundings so I don’t expect anything to happen to it. It’s a very sudden change in temperature that could cause a bloating or the opposite.

Stick to the IT world.

[cyprusgrump]

To cut a long story short, by the time a car drives up a mountain whatever is in that bottle will attain whatever temperature is in its surroundings so I don’t expect anything to happen to it. It’s a very sudden change in temperature that could cause a bloating or the opposite.

No, it doesn't matter how fast or slow the change of temperature is (assuming the bottle is 100% sealed).

Likewise, it doesn't matter how quickly you drive up the mountain (or fly up it) the effect of the decrease in pressure would be the same...

[Get Real!]

To cut a long story short, by the time a car drives up a mountain whatever is in that bottle will attain whatever temperature is in its surroundings so I don’t expect anything to happen to it. It’s a very sudden change in temperature that could cause a bloating or the opposite.

No, it doesn't matter how fast or slow the change of temperature is (assuming the bottle is 100% sealed).

Likewise, it doesn't matter how quickly you drive up the mountain (or fly up it) the effect of the decrease in pressure would be the same...

Air pressure must be directly proportional to air temperature… if it works for liquids and gasses then I see no reason why it shouldn’t apply for air.

But anyway, one can easily simulate this by placing a sealed empty water bottle in the freezer to see what happens. This of course would be a very sudden change and should have the best chances at some kind of effect.

[Get Real!]

To cut a long story short, by the time a car drives up a mountain whatever is in that bottle will attain whatever temperature is in its surroundings so I don’t expect anything to happen to it. It’s a very sudden change in temperature that could cause a bloating or the opposite.

Stick to the IT world.

Stick to your homelessness on the British coast oh daft sufferer of helleniosis!