Naked Science Forum
General Science => General Science => Topic started by: neilep on 10/10/2008 11:49:10
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Wocha Peeps,
See this tyre ?
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Nice eh ?
Tyres are my all time favourite round things made of rubber that vehicles use to get around on.
Say I had a flat tyre (but no puncture) could I use another tyre (say..my neighbours tyres for instance) to partially inflate my own ?....He wouldn't mind !
..To fully inflate my tyre would I just need to utilise a far bigger tyre as the air source ?
Whajafink
Neil
Very Tired
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Just the same as with buckets of water. Two identical tyres would end up at half pressure. Another, donor, tyre of twice the volume would produce 2/3 pressure in both. And so on .
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Hi Neil
the results may not be what you expect; although the pressure might equalise between the two tyres, the volume might not. Have a look at this "two balloons" kitchen science experiment we did on the show recently:
http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/balloons-on-a-tube/
Chris
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Except that balloons are very flexible and a lot of energy is stored in the stretched rubber (the volume / pressure relationship is non-linear) Motor tyres are much more rigid. If the 'empty' tyre is not actually squashed flat then my simple equation would work. I'm not sure how much air would be squeezed out of an uninflated tyre if the car were to be lowered onto it.This would be an added factor. There is only 2Bar of excess pressure in a road tyre so the simple model may not give the right answer.
Air cylinders used in diving work more 'ideally' because the pressures are higher and the 'envelope' can be considered as rigid - In the Navy divers used to decant air from one cylinder to another as part of their dive plan. (More reliable than using a contents gauge).
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Just the same as with buckets of water. Two identical tyres would end up at half pressure. Another, donor, tyre of twice the volume would produce 2/3 pressure in both. And so on .
THANK EWE very much our esteemed Silver Surfer Sophiecentaur !
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Hi Neil
the results may not be what you expect; although the pressure might equalise between the two tyres, the volume might not. Have a look at this "two balloons" kitchen science experiment we did on the show recently:
http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/balloons-on-a-tube/
Chris
Gosh..Thanks Chris...that's great !
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Except that balloons are very flexible and a lot of energy is stored in the stretched rubber (the volume / pressure relationship is non-linear) Motor tyres are much more rigid. If the 'empty' tyre is not actually squashed flat then my simple equation would work. I'm not sure how much air would be squeezed out of an uninflated tyre if the car were to be lowered onto it.This would be an added factor. There is only 2Bar of excess pressure in a road tyre so the simple model may not give the right answer.
Air cylinders used in diving work more 'ideally' because the pressures are higher and the 'envelope' can be considered as rigid - In the Navy divers used to decant air from one cylinder to another as part of their dive plan. (More reliable than using a contents gauge).
Brilliant information...I am learning !!....thank ewe very much !!
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Gases behave more nearly ideally at low pressures and, at low pressures the deformation of the container will be smaller.
If you jack up your car and sit on the other acr when you connect the tyres you will pump slightly more than half the air (assuming identical tyres and similar cars)
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Gases behave more nearly ideally at low pressures and, at low pressures the deformation of the container will be smaller.
If you jack up your car and sit on the other acr when you connect the tyres you will pump slightly more than half the air (assuming identical tyres and similar cars)
[;D]..Now that's a great idea Bored Chemist and now that you've explained it I can see how that works...sounds like a great idea...Thank you very much !
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While you're at it, you may as well borrow your neighbor's petrol as well [;D]
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While you're at it, you may as well borrow your neighbor's petrol as well [;D]
Already siphoned and replaced with bladder contents ! [;D]
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Just the same as with buckets of water. Two identical tyres would end up at half pressure. Another, donor, tyre of twice the volume would produce 2/3 pressure in both. And so on .
THANK EWE very much our esteemed Silver Surfer Sophiecentaur !
You cheeky young whippersnapper!