JEE MAIN - Physics (2020 - 6th September Evening Slot - No. 5)
A fluid is flowing through a horizontal pipe of varying cross-section, with
speed v ms–1 at a point where the pressure is P pascal. At another point where pressure is $${P \over 2}$$ Pascal its speed is V ms–1. If the density of the fluid is $$\rho $$ kg m–3 and the flow is streamline, then V is equal to :
speed v ms–1 at a point where the pressure is P pascal. At another point where pressure is $${P \over 2}$$ Pascal its speed is V ms–1. If the density of the fluid is $$\rho $$ kg m–3 and the flow is streamline, then V is equal to :
$$\sqrt {{P \over {2\rho }} + {v^2}} $$
$$\sqrt {{P \over \rho } + {v^2}} $$
$$\sqrt {{{2P} \over \rho } + {v^2}} $$
$$\sqrt {{P \over \rho } + {v}} $$
Explanation
From Bernoulli's equation,
P + $${1 \over 2}\rho {v^2}$$ = $${P \over 2} + {1 \over 2}\rho {V^2}$$
$$ \Rightarrow $$ V = $$\sqrt {{P \over \rho } + {v^2}} $$
P + $${1 \over 2}\rho {v^2}$$ = $${P \over 2} + {1 \over 2}\rho {V^2}$$
$$ \Rightarrow $$ V = $$\sqrt {{P \over \rho } + {v^2}} $$
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