@JohnRennie sir there?

@satan29 hi :-)

morning sir. DO you know about PID controller?

No, sorry. I had never even heard of it begore you mentioned it.

ok sir no problem

sir I am uploading a tutorial to your server

sir uploaded

Got it

@JohnRennie sir Q.2

Open means matter and heat cross the boundary while closed means only heat crosses the boundary. Yes?

yes

So for example with an Automobile engine fuel enters the system, gets burned, and exhaust gases exit the system. So this is an open system.

right'

So you apply the same criteria to the other systems.

sir pressure cooker is closed?

Though some of them are a bit ambiguous. For example I'd guess a pressure cooker is meant to be closed, but I remember than on my Mum's pressure cooker the pressure valve maintained the pressure by letting steam out. That makes it an open system.

yes thats what confused me a bit too

I don't know what I would answer to that. I'd probably answer open.

sir also we need to "draw the system boundary, and their interactions", what do do for that in q.1 ?

The boundary would be round the engine, so the fuel tank and the exhaust pipe are outside the system.

So fuel flows from the tank across the boundary into the engine and exhaust gases flow out of the engine across the boundary and into the exhaust pipe.

For example, the contents of a pressure cooker on a stove with its lid tightly closed and the whistle in position, is a closed system as no mass can enter or leave the pressure cooker, but heat can be transferred to it. When the whistle of the pressure cooker blows, then it becomes an open system as steam leaves the cooker

2sir even when the pressure cooker is open system

nothing is entering, right?

@satan29 Yes

@JohnRennie sir is refrigerator an open system?

@JohnRennie sir there"

?

@satan29 no, because as long as you keep the door closed the only thing that enters it is electricity.

hmm

sir also, question 3

The gauges measure the pressure difference between the inside of the region they are connected to and the outside. Yes?

hmm yes

So C measures P₂ - P₁

got it.

And we are told that the ambient pressure P₁ = 75 cm

question done

@satan29 OK :-)

p1 is known.

sir, do you know what molal volume is?

cant find anything on the net'

it givs results for molar

molar is per mole while molal is per unit weight i.e. per kilogram.

No, wait.

In solutions molar concentration is moles per litre of solvent while molal concentration is moles per kg of solvent.

yeah

For water the two are very similra since for water one litre weighs on kg.

hmm

"molal volume" seems weird though ...

yeahh..

what about molaL specific heat?

Don't know ...

sir leave this for now.. I wanted to discuss q.6 next

athena.ecs.csus.edu/~reardonf/ThermoNotesI/…

sir can you look at q.6 next?

We'll have to leave this for now as I'm answering another (long) question on databases and can't concentrate on thermodynamics.

sir can you answer this before 5 pm though?

as I have to submit this in the night

and you wont be here in the evening..

I don't know how to do Q6. In fact I don't understand what it is asking.

hmm ok

It seems as though you're expected to assume no heat transport between different levels of the atmosphere so the adiabatic equation $PV^\gamma = const$ applies.

Then that's the problem of solving Laplace's equation for the atmosphere, which gives you an exponential decrease of the pressure with height.