Water coming out of the mouth of a tap and falling vertically in strea

1.	Water coming out of the mouth of a tap and falling vertically in streamline flow forms a tapering column, i.e., the area of cross-section of the liquid column decreases as it moves down. At the mouth of the tap the area of cross-section is 2.5 cm2 and the speed of water is 3 m/s. The area of cross-section of the water column 80 cm below the tap is (a) 2 cm2 (b) 1.5 cm2 (c) 1 cm2 (d) 0.5 cm2
Answer» Correct answer is: (b) 1.5 cm² A₁ = 2.5 cm² , v₁ = 3 m/s, h = 0.8 m, g = 10 m/s² v₂² = v₁² + 2gh = 25 or v₂ = 5 m/s. A₁v₁ = A₂v₂ or A₂ = A₁v₁ / v₂ = 1.5 Cm².

Water coming out of the mouth of a tap and falling vertically in streamline flow forms a tapering column, i.e., the area of cross-section of the liquid column decreases as it moves down. At the mouth of the tap the area of cross-section is 2.5 cm2 and the speed of water is 3 m/s. The area of cross-section of the water column 80 cm below the tap is (a) 2 cm2 (b) 1.5 cm2 (c) 1 cm2 (d) 0.5 cm2

Answer»

Correct answer is: (b) 1.5 cm²

A₁ = 2.5 cm² , v₁ = 3 m/s, h = 0.8 m, g = 10 m/s²

v₂² = v₁² + 2gh = 25 or v₂ = 5 m/s.

A₁v₁ = A₂v₂ or A₂ = A₁v₁ / v₂ = 1.5 Cm².