A garden fountain is fed by a broad pipe of internal diameter 2 cm carrying water at 3 m/s. At the end the water passes through a cap pierced with 100 small holes, each of diameter 0.05 cm. Find the speed (in m/s) with which water jets out of the holes.

0.48
96
24
48

Correct answer: 48

Solution

Conservation of volume flow (incompressible water) means the cross-sectional-area times velocity is the same for the pipe and for all the holes combined.

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