Cyprus-Forum.com

[bill cobbett]

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?

It shouldn't...

But, if the cap was put on at the bottom of the mountain when it was very hot...

... then as the temperature decreased going up the mountain it could perhaps have a greater effect than the decrease in air pressure...

Ah... temperature... must have a think... ( < me thinking)

It's not the temperature. As I wrote above it's the pressure/density change. The difference in pressure between the air trapped inside the bottle and the surroundings causes a force interaction, which in turn causes the crumple.

< Toffoui thinking.

[GreekIslandGirl]

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?

It shouldn't...

But, if the cap was put on at the bottom of the mountain when it was very hot...

... then as the temperature decreased going up the mountain it could perhaps have a greater effect than the decrease in air pressure...

Ah... temperature... must have a think... ( < me thinking)

It's not the temperature. As I wrote above it's the pressure/density change. The difference in pressure between the air trapped inside the bottle and the surroundings causes a force interaction, which in turn causes the crumble.

It's not temperature or pressure. Amazingly, it's all to do with time passing faster at higher altitudes! The bottle is simply degenerating with rapid ageing.

There you go ...

[Get Real!]

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.

[GreekIslandGirl]

Crisp packets expand in de-pressurised airplane cabins.

[Get Real!]

Crisp packets expand in de-pressurised airplane cabins.

Would that be Smiths or Lays?

[GreekIslandGirl]

Crisp packets expand in de-pressurised airplane cabins.

Would that be Smiths or Lays?

It depends which way you are travelling.

[cyprusgrump]

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?

It shouldn't...

But, if the cap was put on at the bottom of the mountain when it was very hot...

... then as the temperature decreased going up the mountain it could perhaps have a greater effect than the decrease in air pressure...

Ah... temperature... must have a think... ( < me thinking)

It's not the temperature. As I wrote above it's the pressure/density change. The difference in pressure between the air trapped inside the bottle and the surroundings causes a force interaction, which in turn causes the crumble.

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

[cyprusgrump]

(The system restricts the number of embedded quotes so I have started a new one...)

But no...

Read the thread...

It was only YOU that was obsessed by the vacuum...

It was only YOU that thought it would be impossible to hear somebody if they were travelling faster than the speed of sound...

It was only YOU that confused attitude and altitude...

It was only YOU that kept posting LONG after your credibility has been exhausted...

As I said, keep clutching at straws if you wish....

On the contrary it was once you started off on sound travelling in a vacuum that I got 'obsessed' with trying to explain to you that he could only be speaking from within his helmet which was full of oxygen - yes, please do go back (in time!).

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

You mean "no friction" from air resistance to affect his speed, right? Because as far as the sound is concerned, he wasn't in a vacuum because he had a helmet on for oxygen!

And I never said anything was "impossible"!

You have once again miss-quoted me...

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

I didn't ever claim that there was a vacuum in his helmet - the only vacuum appears to be within your head....

And yes, if you wish to be pedantic, you didn't say it was impossible for somebody to be heard if they were travelling faster than the speed of sound. Just...

Still trying to come to terms with him going faster than the speed of sound and his microphone not catching what he was saying because he was travelling beyond Mach I. Amazing!

Which started the whole thing off!

[GreekIslandGirl]

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. )

[kurupetos]

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?

It shouldn't...

But, if the cap was put on at the bottom of the mountain when it was very hot...

... then as the temperature decreased going up the mountain it could perhaps have a greater effect than the decrease in air pressure...

Ah... temperature... must have a think... ( < me thinking)

It's not the temperature. As I wrote above it's the pressure/density change. The difference in pressure between the air trapped inside the bottle and the surroundings causes a force interaction, which in turn causes the crumble.

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

Definitely, I didn't claim anything different.