Question

A manometer connected to a closed tap reads 3.5 × 10⁵N/m². When the valve is opened, the reading of manometer falls to 3.0 × 10⁵N/m², then velocity of flow of water is

• A. 100 m/s
• B. 10 m/s
• C. 1 m/s
• D. $10 \sqrt { 10 }$m/s

Answer 1

Answer: (B)

10 m/s

Answer 2

Bernoulli's theorem for unit mass of liquid $\frac { P } { \rho } + \frac { 1 } { 2 } v ^ { 2 } =$

Constant As the liquid starts flowing, it pressure energy

decreases $\frac { 1 } { 2 } v ^ { 2 } = \frac { P _ { 1 } - P _ { 2 } } { \rho }$

$\Rightarrow \frac { 1 } { 2 } \mathrm { v } ^ { 2 } = \frac { 3.5 \times 10 ^ { 5 } - 3 \times 10 ^ { 5 } } { 10 ^ { 3 } } \Rightarrow \mathrm { v } ^ { 2 } = \frac { 2 \times 0.5 \times 10 ^ { 5 } } { 10 ^ { 3 } }$