 Next is a device or a venturi meter which is called a gadaan and which has an edge in it. So what should I do? Nobody cares about who has taught you what. In board exam, some extra person will send the paper. This much, only this much. For a pipe of this thickness, the pipe has this much thickness, something of this size only. The pipe can go on and on. So inside the pipe itself it encounters the venturi meter. So your pipe is there, in between the pipe there is a venturi meter. This procession area, procession area of both sides of the venturi meter will be same. And since you have related venturi meter, these things are known to you. Capital A is known to you and small A is the procession area of the neck. That is also known to you. Now I don't have different classes. In one of the class, I don't create a list in N-Pesa. The way I... I have to... Alright. Some other joke. How it is useful, but right now you first... Suppose P1 is in terms of P1, P2 or small A with V2. Both are same. So please find out what is the value of simpler than that. Just write down. Find out P1 and... Which are my two points? Point number one, point number two. Between these two points I have to write... So P1 plus... Stop talking. I'll just pick someone and ask someone for the answer. See, I can use this as my reference to both are zero. Okay, so rho g h will not appear itself. So P1 plus half rho V1 square is equal to P2 plus... Half rho V2 square. Now tell me where... V2 is... This is more than that. And some of this and that is constant. So please... Let's... If we are not... This is 20. How much this should be? That point has increased. So pressure energy will decrease. Some of the energy is constant. Same. Okay, so that is why people say that... Do not go near... The air which is next to the moving train... What's the train? Okay. Sir, I'm not lying. Is it Pk... What? Some similar incidents? Something similar? What are you talking about? So if you... If you get close to it, you don't get zero. Minus one. Be careful. How it comes? Known... Capital A is known. Small A is known. But P1 and P2... From this side, moving water in the pipe... So you should better use a heavier fluid... Inside the manometer. And that is... Mercury. Okay. So let's say this is Mercury. Density of... Alright. And let's say the height difference... In a gas. Because density is very less. So similar kind of... But you are ignorant. So pressure over here... I can say it is. And P1 is below... From this point of... The pressure here will be more. You forgot that... Law itself. You are telling me minus. So P1 minus P2 is... We have a scale over here. I can substitute the values... What I answer to it is... P1 minus P2 is rho and G edge. The two times... Rho, Mercury, G edge... Divided by small a... The whole square... Minus 1. This is velocity V1... In terms of... Fine. Density of water. Density of water to know... So flow rate is how much? This into... So capital Q is... Flow rate. This much volume of water... Is flowing per... Second in the pipe.