Fluid Mechanics - Mechanics - Physics Previous Year Questions

A frame made of metallic wire enclosing a surface area A is covered with a soap film. If the area of the frame of metallic wire is reduced by 50%, then the energy of the soap film will be changed by

A ball floats on the surface of water in a container exposed to the atmosphere. When the container is covered and the air is partially removed, then the ball

A fluid is in streamline flow across a horizontal pipe of variable area of cross-section. For this which of the following statements is correct?

The surface tension of a liquid at its boiling point

According to Pascal's law, pressure in a fluid at rest is the same at all points, if

A raft of density 600 g/m\(^3\) and mass 120 kg floats in water. How much weight can be put on the raft to make it just sink?

Water is poured in a tank through a cylindrical tube of area of cross-section A and ejecting water at a constant speed 4 m/s. the tank contains a hole of area \(\frac{A}{2}\) at bottom. Level of water in the tank will not go up beyond

Water from a tap of cross-sectional area \(1 \mathrm{~cm}^2\), falls vertically downwards at \(2 \mathrm{~m} / \mathrm{s}\). The cross sectional area of the stream, \(20 \mathrm{~cm}\) below the tap is (assume that pressure is constant throughout and the flow is streamlined; \(\left(\mathrm{g}=10 \mathrm{~ms}^{-2}\right)\)

Modulus of rigidity of an incompressible liquid is

Water flows from a tap with steady flow, through a cross sectional area of \(10^{-3} \mathrm{~m}^2\) with a speed of \(0.5 \mathrm{~ms}^{-1}\). Assume the pressure is constant throughout the stream of water. The cross sectional area of the stream \(0.19 \mathrm{~m}\) below the tap is

What is the relation obeyed by the angles of contact \(\theta_1, \theta_2\) and \(\theta_3\) of 3 liquids of different densities \(P_1, P_2\) and \(P_3\) respectively \((\mathrm{P}_1 < \mathrm{P}_2 < \mathrm{P}_3\)) when they rise to the same capillary height in 3 identical capillaries and having nearly same surface tension \(\mathrm{T}\) ?

64 rain drops of the same radius are falling through air with a steady velocity of \(0.5 \mathrm{~cm} \mathrm{~s}^{-1}\). If the drops coalesce, the terminal velocity would be

The speeds of air-flow on the upper and lower surfaces of a wing of an aeroplane are \(v_1\) and \(v_2\), respectively. If \(A\) is the cross-sectional area of the wing and \(\rho\) is the density of air, then the upward lift is

A block of wood floats in water with \((4 / 5)\) th of its volume submerged. If the same block just floats in a liquid, the density of the liquid is (in \(\mathrm{kgm}^{-3}\))

A balloon with mass $m$ is descending down with an acceleration \(a\) (where, \(a < g\) ). How much mass should be removed from it so that it starts moving up with an acceleration \(a\) ?

A small hollow vessel which has a small circular hole of radius $r$ in its base, is immersed in a tank of oil of density $\rho$ and surface tension $T$. The oil will penetrate into the vessel at a depth of