Calculate the discharge in litres per minute of a venturi-meter if it is of 86 cm diameter in main part and of 10 cm diameter in neck part. Specific gravity of Hg=13.6 and difference of pressure of water between mains and neck is 20 cm of Hg.

Explanation

To calculate the discharge in litres per minute of a Venturi-meter with given diameters and pressure difference, we will follow these steps:

### Step 1: Convert the pressure difference from cm of Hg to meters of water.
The pressure difference is given as 20 cm of Hg. We can convert this to meters of water using the specific gravity of mercury (Hg).

\[ H = \text{Pressure difference} = 20 \, \text{cm Hg} = 20 \times 13.6 \times 10^{-2} \, \text{m of water} \]
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