Project ForgeWater is coming out from a tap and falls vertically downwards. At the tap opening, the stream diameter is 20 mm with uniform velocity of 2 m/s. Acceleration due to gravity is 9.81 m/s². Assuming steady, inviscid flow, constant atmospheric pressure everywhere and neglecting curvature and surface tension effects, the diameter in mm of the stream 0.5 m below the tap is approximately
- A10
- 15
- C20
- D25
Explanation
Velocity 0.5m below (free fall, energy conservation): V1=√(V0²+2gh)=√(4+2×9.81×0.5)=√13.81≈3.716 m/s. Continuity (mass conservation): D0²V0=D1²V1, so D1=D0·√(V0/V1)=20×√(2/3.716)=20×0.7336≈14.7 ≈ 15 mm.
Source: GATE ME 2013 (Booklet Code A) (2013)
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