00:01
Now here in this question, we have two later questions.
00:03
The first one is about one kilogram of air, right? so suppose you have one kilogram of air, the mass of this air is one kilogram, and you can work out, of course, how many moles of air is there, right? so let the more be n, it's given by m divided by the motor mass of air, which is about, i think, let me, it's easy to find this on several, so it's roughly about 20 easy work out how many models of this area is.
00:49
It goes as a solar expansion.
00:51
So it's a constant temperature expansion.
00:53
If you look at the expansion in the pv, you will see that this actually goes like this, right? so this is basically this two volumes.
01:04
So according to the question, at the beginning, at the beginning, which of course, this is the beginning point.
01:12
And this is the antipone rate.
01:15
The air was at temperature, suppose at this point, the temperature at this point, i would call t -0, which is 20 degrees, so that's 293 caravans, right? it has a brazier, which is, of course, here.
01:29
I call it p -0, which is 3 megapascal, right? and the u .s.
01:36
And you add, you know, the semi -expansion processes happens, by adding this much energy to it, which is 100 kilojou energy, okay, to the air and the air expands as summary, right? so you are asked to find basically the, you ask you to find the initial and the final volume of the air, right? so the initial volume, i call it v0, and the final volume i will just call it v, all right? and you're asked to find this, volume here, right? so, you know, the initial volume can easily work it out using the equation of state for the idea gas.
02:24
That is p0 times v0 equals nr times t0, right? now, all is the gas constant, right? and n is known from this equation.
02:34
So you find that a v0 is just given by n r t0 divided by p .0, right? all the quantities involved in this inspiration are known.
02:42
So you can use the calculator easy to work out the pressure.
02:46
I'll leave you to do that.
02:48
Then how do you work out the final pressure? well, the idea is to note that during this as a storm expansion, the temperature is kept a constant, so the total internal energy of the air does not change.
03:00
In other words, the energy supplied to the air, q is completely converted into the work down to the outside.
03:09
So q must be exacted to equal to the air.
03:12
Work during this expansion process, which actually is given by n r t times logarithm v over v .0.
03:22
Now from this equation is very clear that v is just given by it's just given by 0 times e q over n rt.
03:33
So that's the final one you can expect of the air after the expansion.
03:41
I'll leave you to plug the values for the queue, which is giving about the question, everything is given by the question to use a calculator to work out the numerical value with this value.
03:53
And there's another question about autosacchar, right? of course, this is the basis of all modern engines, right? so let me, for your convince, let me just remind you what autosacre is, right? so here is a diagram in the pv plane, what the auto -saccair looks like is basically this auto -sacker.
04:20
You know, that's what's happening...