JEE Main201910 Apr 2019Evening ShiftPhysicsMechanical Properties of FluidsActual
Water from a tap emerges vertically downwards with an initial speed of 1.0 m s - 1 . The cross - sectional area of the tap is 10 - 4 m 2 . Assume that the pressure is constant throughout the stream of water and that the flow is streamlined. The cross - sectional area of the stream, 0.15 m below the tap would be: (Take g = 10 m s - 2 )
Options
- A1 × 10 - 5 m 2
- B5 × 10 - 4 m 2
- C2 × 10 - 5 m 2
- D5 × 10 - 5 m 2
Correct answer
D. 5 × 10 - 5 m 2
Step-by-step solution
Velocity of water after falling through distance 0.15 m is v 2 = u 2 + 2 a s = 1 + 2 × 10 × 0.15 v 2 = 4 v = 2 m / s From equation of continuity A 1 v 1 = A 2 v 2 A 2 = 10 - 4 × 1 2 = 5 × 10 - 5 m 2