Answer to Question #100489 in Field Theory for Derickson

Question

Calculate the discharge in litres per second and the time required to discharge 300 000 litres of water from a swimming pool by means of a 76mm diameter short pipe, having a bell shape connection when there is a constant head of water above the centre of the pipe of 2 meters

Answer 1

The discharge:

$$Q=C_d A\sqrt{2gh}$$

$$Q=(0.97)(0.25\pi (0.076)^2)\sqrt{2(9.81)(2)}=0.02756\frac{m^3}{s}$$

$$Q=27.56\frac{litre}{s}$$

Time:

$$T=\frac{V}{Q}=\frac{300000}{27.56}=10885\ s=3.024\ h$$