List of top Physics Questions on Fluid Mechanics

Match the law/principle with the concerned application: \[ \begin{array}{|c|c|} \hline \textbf{Application} & \textbf{Law / Principle} \\ \hline a)\ \text{Hydraulic Lift} & i)\ \text{Bernoulli's Principle} \\ \hline b)\ \text{Speed of Efflux} & ii)\ \text{Torricelli's Law} \\ \hline c)\ \text{Dynamic Lift} & iii)\ \text{Stoke's Law} \\ \hline d)\ \text{Viscous Drag Force} & iv)\ \text{Pascal's Law} \\ \hline \end{array} \]
A thin metal disc of radius \(r\) floats on water surface and bends the surface downwards along the perimeter making an angle \(\theta\) with vertical edge of the disc. If the disc displaces a weight of water \(W\) and surface tension of water is \(T\), then the weight of metal disc is
A liquid flows with velocity $2$ m/s through a pipe of diameter $0.01$ m. Density = $1000$ kg/m$^3$, viscosity = $0.5$ kg/m$\cdot$s. Reynolds number is:
On opposite sides of a wide vertical vessel filled with water (density \(ρ\)), two identical holes are drilled, each having cross-section area \(A\). The height difference between holes is \(x\). The resultant force of reaction of water flowing out of vessel is (\(g\) = acceleration due to gravity)
An in-compressible fluid flows steadily through a horizontal cylindrical pipe. The pipe has radius '\(3R\)' at point A and '\(1.5R\)' at point B, further along the flow direction at the same level. If the velocity at point A is '\(v\)', then that at point B is
An incompressible fluid (ideal fluid) is flowing through non uniform cross-sectional tube PQ as shown in the figure from end P to end Q. If \(K_P\) and \(K_Q\) are the kinetic energy per unit volume of the fluid at end P and end Q respectively, then
In case of fluid flowing on horizontal surface the flow of fluid becomes unsteady when Reynolds number (Rn) is
A horizontal pipe carries water in a streamline flow. At point along the pipe, where the cross-sectional area is \(A_1\), the velocity of water is \(V_1\) and the pressure is \(P_1\). What is the pressure of water at another point where the cross-sectional area is \(A_2\)?
Water flows through a horizontal pipe at a speed 'V'. Internal diameter of the pipe is 'd'. If the water is emerging at a speed '\(V_1\)' then the diameter of the nozzle is
A closed pipe containing liquid showed a pressure \(P_1\) by gauge. When the valve was opened, pressure was reduced to \(P_2\). The speed of water flowing out of the pipe is (\(ρ\)=density of water)
Water flows through a horizontal pipe. At one point, the velocity is \(2\ \text{m/s}\) and the pressure is \(2\ \text{m}\) of water column. What is the pressure at another point where the velocity is \(3\ \text{m/s}\)?
(Density of water \(=10^3\ \text{kg/m}^3\))
Water flows through a horizontal pipe. At one point, the velocity is $2~m/s$ and the pressure is $2~m$ of water column. What is the pressure at another point where the velocity is $3~m/s$?
(Density of water $=10^3~kg/m^3$)
Two capillary tubes of radii \(r_1\) and \(r_2\) \((r_1 > r_2)\) are dipped vertically in the same liquid. The rise of liquid in the tubes \(h_1\) and \(h_2\) satisfies:
Water flows through a horizontal pipe. At one point, the velocity is 2 m/s and the pressure is 2 m of water column. What is the press another point where the velocity is 3 m/s? (Density of water = 10³ kg/m³)
The thickness of the ice layer on the surface of a lake is 20 m. A hole is made in the ice layer. What is the minimum length of the rope required to take a bucket full of water?
An enclosed container filled with gas is moving in a horizontal direction with some acceleration. Neglecting the gravitational force, the pressure of the gas inside the container will be
The flow velocity of water from a tap is 3 liters/min. If the diameter of the tap is 1.25 cm and the viscosity of water is \( 10^{-3} \) Poise, then the value of Reynolds number is approximately
Water flows through a horizontal pipe of varying cross-section at the rate of \( \pi \times 10^{-1} \, \text{m}^3/\text{s} \). The velocity of water at a point where the radius of the pipe is 10 cm is \( (\pi = 3.14) \)
Same current is flowing in two different a.c. circuits. First circuit contains only inductance and second contains only capacitance. If the frequency of a.c. is increased in both circuits, the current will
Water is flowing steadily in a river. A and B are the two layers of water at heights $40 \text{ cm}$ and $90 \text{ cm}$ from the bottom. The velocity of the layer A is $12 \text{ cm/s}$. The velocity of the layer B is
A liquid drop splits into \(729\) identical spherical drops. If \(E\) is the original energy and \(U\) is the total resulting energy , then \(E/U = 1/x\). The value of \(x\) is.
A vessel completely filled with water has two holes 'P' and 'Q' at depths '(2h)' and '(8h)' from the top respectively. Hole 'P' is square of side '(a)' and hole 'Q' is a circle of radius '(r)'. If the water flowing out per second from both is same, then side '(a)' is
An electric dipole of dipole moment ' \(p\) ' is aligned parallel to a uniform electric field ' E '. The energy required to rotate the dipole by \(90^\circ\) is \( \begin{bmatrix} \sin 0^\circ = 0, & \sin 90^\circ = 1 \\ \cos 0^\circ = 1, & \cos 90^\circ = 0 \end{bmatrix} \)
A liquid drop splits into \(729\) identical spherical drops. If \(E\) is the original energy and \(U\) is the total resulting energy , then \(E/U = 1/x\). The value of \(x\) is.
A vessel completely filled with water has two holes 'P' and 'Q' at depths '(2h)' and '(8h)' from the top respectively. Hole 'P' is square of side '(a)' and hole 'Q' is a circle of radius '(r)'. If the water flowing out per second from both is same, then side '(a)' is