Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-l] App. for Was: Re: T dS versus dQ



I wrote:

Bob LaMontagne wrote:

... If ... one applies a force with one's hand to push the piston to the
stop in 10 seconds - and then repeat with identical apparatus but
do the compression in 0.001 seconds, and then let the two pieces of
apparatus sit for a while until all waves. etc., dissipate, ... will the
final temperatures and pressure be higher?

Both will be higher than they would have been had the process been
quasistatic. This is a simple deduction from the fact that the
entropy will be higher because of the fact that dissipation has
occurred. They will also almost certainly be different.

On second reading, I realize that the above may be confusing without the explanation that it was predicated on the idea that neither the 10 second compression or the .001 second compression is strictly "quasistatic." My final sentence was referring to the results of these two different non-quasistatic processes as compared to a third, strictly quasistatic compression. I see now that Bob surely intended for the first to constitute an extremely good approximation to a quasistatic compression which it certainly would for, say, a container with a volume on the order of liters.

John Mallinckrodt
Cal Poly Pomona