Question

To water the yard, you use a hose with a diameter of 3.5 cm . Water flows from the hose with a speed of 1.5 m/s . If you partially block the end of the hose so the effective diameter is now 0.52 cm , with what speed does water spray from the hose?

Answer 1

Answer 2

SOLUTION 

Flow rate remains unchanged.

Let v1 m/s be speed of water after partial blocking.

So,

Q with no partial blocking = Q after partial blocking

=> A0 * v0 = A1 * v1

=> pi/4 (3.5/100)^2 * 1.5 = pi/4 (0.52/100)^2 * v1

=> (3.5)^2 *1.5 = (0.52)^2 * v1 

=> v1 = (3.5/0.52)^2 * 1.5

=> v1 = 67.95 m/s (ANSWER).