eeeers a question!!
09 July 2003, 02:16 PM
#1
Scooby Regular
Thread Starter
Does the air particles in a tyre turn at the same speed as the tyre and wheel? Or do they stay stationery with the tyre and wheel moving around them. And, if they do turn with the wheel, when you stop the car do the particles continue to circle around for a short time.
09 July 2003, 04:36 PM
#4
Scooby Regular
Join Date: Apr 2003
Location: A galaxy far far away.
Posts: 3,310
Likes: 0
Received 0 Likes
on
0 Posts
the air paricles in the tyre will bounce around the inside of the tyre in a random direction, bouncing all over the shop, all the time the tyre is inflated.
so....................... no.
so....................... no.
09 July 2003, 04:44 PM
#5
Scooby Regular
Thread Starter
I thought particles (or molecules to more accurate) wouldn't bounce everywhere, but would just vibrate around a fixed point (remember your 'brownian motion' experiment at school).
All particles must follow the laws of inertia, so the rotating tyre and wheel wall must push some particles of air around with them, which in turn will force other particles to turn.
All particles must follow the laws of inertia, so the rotating tyre and wheel wall must push some particles of air around with them, which in turn will force other particles to turn.
09 July 2003, 04:56 PM
#6
Scooby Regular
So.....no external forces (outwith the tyre) are at work apart from temperature and vibration from the road ..........
Therefore.... the molecules would heat up and would start being a bit more 'active'
Would this then create a 'skin' of molecules around the inner edges of the tyre that would be affected by the movement of the tyre and then leave another segment (inner lot) that will just buzz around their fixed point? But would this inner lot then get affected by the behaviour of the ones nearer the rubber bits....
But what about the centrifugal forces at work on the particles being thrown out from the centre
PS I failed O grade physics so I'm just throwing my 2p's worth in to spark further debate and I still ain't sure if they actually go around or not
Tomorrow I probably won't give a toss but it's got me thinking this aftertnoon
Therefore.... the molecules would heat up and would start being a bit more 'active'
Would this then create a 'skin' of molecules around the inner edges of the tyre that would be affected by the movement of the tyre and then leave another segment (inner lot) that will just buzz around their fixed point? But would this inner lot then get affected by the behaviour of the ones nearer the rubber bits....
But what about the centrifugal forces at work on the particles being thrown out from the centre
PS I failed O grade physics so I'm just throwing my 2p's worth in to spark further debate and I still ain't sure if they actually go around or not
Tomorrow I probably won't give a toss but it's got me thinking this aftertnoon
Trending Topics
09 July 2003, 05:04 PM
#8
Scooby Regular
Join Date: Jun 2000
Posts: 4,413
Likes: 0
Received 0 Likes
on
0 Posts
The air would act like any other fluid. At first, the molecules in contact with the rotating tyre/wheel would start to move due to friction. These would then transfer there momentum to other further inside. And so on until all of the air is moving in the same rotating direction (but at different speeds - fastest on outside).
09 July 2003, 09:46 PM
#10
Scooby Regular
Thread Starter
So when the car stops does the air continue to circle around the tyre - and if you brake hard does all the air molecules hit the front tyre wall, like a head would hit a windscreen
09 July 2003, 10:09 PM
#13
Scooby Regular
Join Date: Apr 2003
Location: A galaxy far far away.
Posts: 3,310
Likes: 0
Received 0 Likes
on
0 Posts
let us remember there is no such thing as sentrifugal force - only sentripetal. But that doesnt matter, the molecules wont be effected.
the gas molecules will only move randomly. Inside the tyre is like having 10 guys constantly teeing off in a sqaush court, would it make a difference to the crazy randomly moving golf ***** if the squash court was spinning?????
mmmmmmmmmmmmmmm not really.
the gas molecules will only move randomly. Inside the tyre is like having 10 guys constantly teeing off in a sqaush court, would it make a difference to the crazy randomly moving golf ***** if the squash court was spinning?????
mmmmmmmmmmmmmmm not really.
10 July 2003, 10:36 AM
#16
Scooby Regular
Join Date: Jun 2000
Posts: 4,413
Likes: 0
Received 0 Likes
on
0 Posts
let us remember there is no such thing as sentrifugal force - only sentripetal.
But that doesnt matter, the molecules wont be effected.
the gas molecules will only move randomly. Inside the tyre is like having 10 guys constantly teeing off in a sqaush court, would it make a difference to the crazy randomly moving golf ***** if the squash court was spinning?????
mmmmmmmmmmmmmmm not really.
mmmmmmmmmmmmmmm not really.
Look at it this way....
Take a bowl of water. Place the bowl on a rotating suface, or float in a bath or something to allow it to rotate. Now spin the bowl around. At first the water inside the bowl is stationary in relation to the bowl, but as the water in contact with the surface of the bowl is effected by friction, it too starts to move. This is turn effects the water furtur in until all the water is moving at (or near) the spead of the bowl. When you suddenly stop the bowl, you will see the water continues to rotate, until it is eventually slowed by fritction.
The same thing happens to the air in your tyres. Both are fluids and act in the same way.
10 July 2003, 11:35 AM
#17
Scooby Regular
Join Date: Feb 2002
Posts: 1,377
Likes: 0
Received 0 Likes
on
0 Posts
I suggest you all go and read exacly what forces are needed for molecules the size of nitrogen to hold a tyre at ~30psi, then go and read about fluid dynamics.... yawn.
In short, at 30 psi nitrogen molecules have an rms^2 velocity of ~2000ms^{-1}, the speed of the vehicle is negligible. i.e is doesn't matter.
In short, at 30 psi nitrogen molecules have an rms^2 velocity of ~2000ms^{-1}, the speed of the vehicle is negligible. i.e is doesn't matter.
10 July 2003, 12:20 PM
#23
Scooby Regular
iTrader: (2)
Join Date: May 2000
Location: Class record holder at Pembrey Llandow Goodwood MIRA Hethel Blyton Curborough Lydden and Snetterton
Posts: 8,626
Likes: 0
Received 0 Likes
on
0 Posts
I'd have thought that any effect the rotating tyre has on the random direction and momentum changes of a gas particle @ 30 psi would be negledgable, so in theory yes but in practice its just some air in a tyre FFS
11 July 2003, 02:36 PM
#30
Scooby Regular
Join Date: Jul 2002
Location: Lyon
Posts: 571
Likes: 0
Received 0 Likes
on
0 Posts
Sad, I know,
But a quick calc says on a standard 16" rim, running at 32 psi tyre pressure and 40C, inflating with Helium would reduce the unsprung weight by 378 grammes.
But a quick calc says on a standard 16" rim, running at 32 psi tyre pressure and 40C, inflating with Helium would reduce the unsprung weight by 378 grammes.