Recent content by AbhiNature

Chacabucogod, For Carnot's cycle, efficiency is independant of energy or power. The gas contraction that you mentioned from 30C to 20C or 10C is not a part of Carnot's cycle. That is not a reversible process. Power from Carnot's engine would be same for any temperatures because isothermal...

Two different reversible cycles that have different efficiencies at the same operating temperatures when used in conjugation will create a PMM of second kind. One that is more efficient can be used to drive the second(now used as heat pump instead of engine). This will pump more heat from the...

Also Carnot's cycle is not only the upper limit but the only efficiency that is available for a reversible engine at given working temperatures.

Because in Carnot's cycle work is done only in isothermal process(addition or rejection), and for ideal gases isothermal process is independant of gas(or the adibatic index). W = nRTln(P2/P1). With the change in ideal gas only adiabatic expansion would affect, and therefore, this wouldn't make...

Not excatly. V^2 = 2GM/R gives the initial speed required for the mass or rocket in your case to move out of gravity field. If an object has this speed in an opposite direction to that of the force of gravity then no further energy is required to propel that object out of that gravity field...

I thought so. It is as improbable to create a lesser efficient reversible engine (compared to Carnot's) as to create a more efficient reversible engine. Whenever second law is violated, maybe, it would be due to the lesser efficient engine.

Is is possible to have 2 different engines with all the following criterion? 1) Are reversible 2) Work differently (different cycles) 3) At the same working temepratures have different efficiencies. E.g. Working temperatures 100K and 50K. Engine 1: Carnot's Efficiency - 50%...

In my opinion it would be wrong to consider finding probability of something once you know its outcome. What is the probability of 2 of heart coming from a well shuffled 52 cards? That would be 1/52. Once a card is chosen there is no question of probability. Though what can be said even...

I was considering a hypothetical scenario where entropy is at its maximum. Instead of Universe it could be any isolated system where entropy is at its maximum and there's a parabolic mirror floating with an object at its focus. The object's temperature will be above that of the bacground radiation?

Scenario: Entropy of the system or say the Universe is at its maximum, and there's a parabolic mirror floating in space with an object at its focus. Due to CMBR the object at focus will heat above the CMBR. Oh! Is there something wrong?

Thanks Darwin and Q_Goest! The information is there in the NIST site that Q_Goest mentioned. Entropy of liquid nitrogen at 1bar pressure and 77.244K is 79.313J/moleK. I was quite off the mark. I will like to close this thread now. Thank you!

Well, finding entropy of liquid nitrogen is more difficult than I thought. As a rough approximition, I took it 120J/moleK. Following is the reason; EN2(liquid) = (EBr2(liquid)/EBr2(gas))*EN2(gas) EN2(liquid) = (152/245)*192 = 120 I guess, this should be close enough.

Thanks for your reply. I will like to add few things. A correction - I have the entropy of nitrogen gas at 100K. Not of liquid nitrogen at 100K. The equation from which I derived the entropy recommends to use it in the temperature range of 100K-500K. It might be safe to extrapolate...

Hi All, I tried to find entropy of liquid nitrogen in various data books, using nitrogen's CAS number, MSDS, but I was able to get the entropy of nitrogen till only 100K, not below that. Does anyone know what's the entropy of liquid nitrogen or that where can I find it? Thanks!

No reply? Not even an opinion?