Question

At what velocity does water emerge from an orifice in a tank in which gauge pressure is $ 3 \times 10^{5} N\,m^{-2} $ before the flow starts? (Take the density of water $ = 1000 \,kg \,m^{-3} $ .)

• A. $ 24.5 \,m\, s^{-1} $
• B. $ 14.5 \,m \,s^{-1} $
• C. $ 34.5\, m\, s^{-1} $
• D. $ 44.5\, m\, s^{-1} $

Answer 1

Answer: (A)

Here, $ P =3\times10^{5}\, Nm^{-2}, \rho=1000\, kgm^{-3}, g=9.8 \, ms^{-2} $
As $ P=h\rho g $
$ \therefore h=\frac{P}{\rho g}=\frac{3\times10^{5}}{1000\times9.8}m $
Velocity of efflux,
$ v=\sqrt{2 gh}=\sqrt{\frac{2\times9.8\times3\times10^{5}}{1000\times9.8}} $
$ =\sqrt{600}=24.495 ms^{-1} \approx24.5\, ms^{-1} $