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[Scalyback]

[center]


Two physical systems are in thermal equilibrium if no heat flows between them when they are connected by a path permeable to heat. Thermal equilibrium obeys the zeroth law of thermodynamics.



I retire to the sidelines quick...

[Revband]

Correct, no heat flows when they are at the same temperature, "In a state of thermal equilibrium".

[jefrs]

That's the simplistic definition, it's also used on dynamic systems where one side is hot, or heated, and the other cold or cooled or being heated, like a household radiator; the temperature of the room will be maintained by the heat from the radiator which is at a higher temperature than it is. If you open the door room temperature will drop and rise back to equilibrium when it's shut again. "Equilibrium" means balanced i.e. heat input equals heat losses (heat is not temperature).

[Revband]

Jeffrs unfortunately you are wrong again, what you refer to there is the second law of thermodynamics which relates to heat transfer, Zeroth law of thermodynamics is different, Zeroth law is as follows.

A system is said to be in thermal equilibrium when it experiences no change in its observable state over time. The most precise statement of the zeroth law is that thermal equilibrium constitutes an equivalence relation on pairs of thermodynamic systems. In other words, the set of all equilibrated thermodynamic systems may be divided into subsets in which every system belongs to one and only one subset, and is in thermal equilibrium with every other member of that subset, and is not in thermal equilibrium with a member of any other subset. This means that a unique "tag" can be assigned to every system, and if the "tags" of two systems are the same, they are in thermal equilibrium with each other, and if they are not, they are not.

You never quite know who you are talking to on the internet do you?

[nigelphoto]

Its that old chestnut again, isn't it? I mean, 'average temperature'. You know the one - feet in the oven, head in the fridge and you've reached 'thermal equilibrium'. We've come a long way from my question on why a blanket on the exhaust pipe but as it happens I was at Newark yesterday and Tom Armitage's record breaking 1989 500 Bullet (Elvington 20th Sep 2015 flying km and standing start mile if you need to know) had a full exhaust wrap. AND I forgot to ask why . . . in the heat of the moment, as it were.

[Bullet Whisperer]

How fast did this Bullet go at Elvington, out of interest? We had 110.5 mph from our 500 Bullet on Pendine sands a few years back, with no wrap on the exhaust and a rather tired engine, as we later discovered - should I maybe expect it to go faster with a wrapped exhaust? Opinions, please, Paul Henshaw.

[Presto]

Paul do you mean 'with' exhaust wrap or 'because' of exhaust wrap? The former is a possibility, depending on what else you do to that, already excellent, machine; the later is unthinkable!

[Bullet Whisperer]

Hi Presto, either way, really, but if someone can tell me the bike should go faster with the exhaust pipe wrapped [and why this should be], I might just try it, perhaps on our next dyno run, at any rate. Judging by the number of machines I have seen at VMCC and other, modern race days, where nearly all of the exhaust pipes are bare metal, usually with heat dispersant black paint on them, I seriously doubt it would do any good. I can recall one Velo 500 that was meant to be quite fast, which had exhaust wrap on the pipe, the owner believing it helped boost power, but other 500's including ours could beat it. As far as I know, the Linsdell Enfield runs with a bare pipe, too. Regards, Paul.

[simon]

I put Armor All on my previous Ducati seat once a long time ago. Took the wife (then girlfriend) for a ride up to her mother's in the Blue Mountains. Thought I'd see if I could hit the ton on the freeway but discovered that we were both sliding off the seat and for a brief moment whilst she shouted "are you trying to F--king kill me" in my ear I genuinely thought we were going to go off the back at what was approaching the 160kmph mark (on the Vague Liars anyway) sliding back equalling throttle on as it does. After what was probably only a couple of seconds but felt like a lifetime I thought of the footbrake. So never put silicon polish on a seat was the lesson.

[simon]

Sorry all was responding to a comment on the first page didn't realize how far you'd progressed on this thread.