Properties Of Solids And Liquids Question 212

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

Options:

A)100 m/s

B)10 m/s

C)1 m/s

D) $ 10\sqrt{10} $ m/s

Show Answer

Answer:

Correct Answer: B

Solution:

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

$ =\frac{2\times 0.5\times 10^{5}}{10^{3}}\Rightarrow v^{2}=100\Rightarrow v=10\ m/s $



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