The rate at which water comes out of a house is directly proportional to the square of the hose’s diameter.
a. If a hose of diameter 3cm gives out water at the rate of 3.6 litres/ second find the rate at which water comes out of a fireman’s hose which is 8cm across.
b. What diameter hose do I use if I want water to come out at 1 litre/ second?
a. w α d^{2
}w = kd²
3.6 = k × 3^{2
}k = 0.4
w = 0.4d^{2}
if d = 8
w = 0.4 × 8^{2}
w = 25.6L/s
b. 1 = 0.4d^{2}
2.5 = d^{2}
d = 1.58cm