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 $
