A water spray gun is connected to a hose of cross-sectional area 30 cm². The gun has 10 identical perforations, each of cross-sectional area 15 mm². Water flows in the hose with speed 50 cm·s⁻¹. Neglecting edge effects, what is the speed of water emerging from each perforation?
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Question

A water spray gun is connected to a hose of cross-sectional area 30 cm². The gun has 10 identical perforations, each of cross-sectional area 15 mm². Water flows in the hose with speed 50 cm·s⁻¹. Neglecting edge effects, what is the speed of water emerging from each perforation?

Options

G1 Physics · Accepted Answer

Use the continuity equation: A(hose)v(hose) = 10A(hole)v(out). Convert the perforation area: 15 mm² = 0.15 cm². Therefore, v(out) = [30×50] ÷ [10×0.15] = 1500 ÷ 1.5 = 1000 cm·s⁻¹. Converting to SI units: 1000 cm·s⁻¹ = 10 m·s⁻¹. Correct option: B.