Question

Water is flowing continuously from a tap having an internal diameter 8 x 10^-3 m. The water velocity as it leaves the tap is 0.4 mis. The diameter of the water stream at a distance 2 x 10^-1 m below the tap is close to:

(a) 7.5 x 10^-3 m

(b) 9.6 x 10^-3 m

(c) 3.6 x 10^-3 m

(d) 5.0 x 10^-3 m

Answer 1

Correct option is : (c) 3.6 x 10^-3 m

By equation of continuity.

(a x v)_top = (a x v)_bottom

vb² - (0.4)² = 2 x 9.8 x 0.2 (∵ v² = u² + 2gh)

∴ vb = 2m/s nearly

π(8 x 10^-3) x 0.4 = πd² x 4

∴ d = 3.6 x 10^-3 m