Suppose you have the air inside a tire travelling down the length of the tire (that is, in circular motion inside the tire). Now as the air slows down inside the tire, what happens to the tire pressure?
Is this like a rolling tire stopping, or is the tire stationary the entire time? Also, where on the tire are you measuring pressure? Do you want to account for Bernouli effects, or deformation of the tire due to it resting on the ground?JohnDubYa said:Suppose you have the air inside a tire travelling down the length of the tire (that is, in circular motion inside the tire). Now as the air slows down inside the tire, what happens to the tire pressure?
There is no friction against the ground. The tire is laying flat on the ground, with the air moving inside the tire. Over time, the air slows down.There are several factors involved in this situation...so its hard to tell now. You have bernouli affects, centripital acceleration, friction against the ground.
Does the pressure drop? Bernoulli's effect is easy to explain in terms of flat surfaces, but curved surfaces are another matter.Lets think about this, the car is moving, since air has very little friction, it takes a long time for it to start circulating. When it circulates, you have the air pressure drop from bernouli affects.
Again, the tire is lying flat on the ground, not standing vertically.The centripital force makes the air molecules pile up on the bottom of the tire, therefore, having a higher pressure.
This effect has little to do with temperature. It takes quite awhile to heat the interior of a tire, yet the inflation occurs immediately once they begin spinning at high speed. (This effect is due to the inertia of the tread.)If you have seen top fuel drag cars there rear tyres are virtually flat until they wheel spin and heat up (which increases the pressure). when they cool down they diflate again.
There is friction between the interior of the tire and the gas in it, and gas-gas friction like in a viscous fluid. It might take a while, and warm up the air a little, but the air will at, least in net, be moving with the tire after a while spinning at the same speed.cyrusabdollahi said:Why would the air go round with the tire?