Mechanical properties of fluids practice · Mixed difficulty

Water does not wet an oily glass because

The lift of an air plane is based on

Due to capillary action, a liquid will rise in a tube. If the angle of contact is

Express standard atmospheric pressure in bars.

In Bernoulli’s theorem which of the following is conserved?

A cylinder drum, open at the top, contains 15 L of water. It drains out through a small opening at the bottom. 5 L of water comes out in time ${t_1}$, the next 5 L in further time ${t_2}$ and the last 5 L in further time ${t_3}$. Then

Surface tension of a liquid is numerically equal to

Find the increase in pressure required to decrease the volume of water sample by $0.01 \%$. Bulk modulus of water $=2.1 \times 10^9 {Nm}^{-2}$

A barometer kept in an elevator reads $76 \mathrm{~cm}$ when it is at rest. If the elevator goes up with increasing speed, the reading will be

Water is flowing through a tube of non-uniform cross-section. Ratio of the radius at entry and exit end of the pipe is 3:2. Then the ratio of velocities at entry and exit of liquid is

A: Needle placed carefully on the surface of water may float, where as a ball of same material sinks
R: Archimedes principle is applicable for only spherical bodies

A soap bubble of radius $R$, surface tension $T$ exists in equilibrium in vacuum. A monoatomic gas is trapped inside the soap bubble. Charge $\mathrm{Q}$ is given to bubble such that bubble expands from radius a to radius $2 \mathrm{a}$ under reversible adiabatic condition. If surface charge density on the bubble surface is found to be $\sqrt{\frac{x \varepsilon_0 T}{y a}}$. Find the value of $x / y .(x, y$ are positive co-primes)

An air foil has:

A spherical ball of radius $1 \times 10^{-4} \mathrm{~m}$ and density $10^5$ $\mathrm{kg} / \mathrm{m}^3$ falls freely under gravity through a distance $h$ before entering a tank of water, If after entering in water the velocity of the ball does not change, then the value of $h$ is approximately :

(The coefficient of viscosity of water is $9.8 \times 10^{-6}$ $\left.\mathrm{N} \mathrm{s} / \mathrm{m}^2\right)$

The excess pressure inside a spherical drop of water is four time that of another drop. Then their respective mass ratio is

A tank is filled with water of density $1\mathrm{gc}{\mathrm{m}^{ - 3}}$ and oil of density $0.9\mathrm{gc}{\mathrm{m}^{ - 3}}$ . The height of water layer is 100 cm and of oil layer is 400 cm. If $\mathrm{g} = 980\mathrm{cm }{\mathrm{s}^{ - 2}}$ , then the velocity of efflux from an opening in the bottom of the tank is

The absolute pressure acting on a horizontal submarine is $4 \times 10^5 \mathrm{~Pa}$ at a certain depth of ocean. If the depth of submarine is doubled, the percentage increase in the absolute pressure acting on the submarine would be:

(1 atm $=10^5$ Pascal, $g=10 \mathrm{~m} / \mathrm{s}^2,$ $\rho_w=10^3 \mathrm{~kg} / \mathrm{m}^3)$

A block of volume $V$, floats in water with volume $\frac{V}{2}$ inside the water surface, now same block placed in another liquid, then floats with volume $\frac{V}{4}$ inside the liquid, then density of the liquid (in ${g} / {cm}^3$ ) is

In a turbulent flow, the velocity of the liquid in contact with the walls of the tube is

The pressure on a swimmer, $10 {~m}$ below the surface of water is (let $g=10 {~m} / {s}^2$ and $1 {~atm}=10^5 {~N} / {m}^2$ )

The excess pressure in a bubble of radius R of a gas in a liquid of surface tension S is

Express standard atmospheric pressure in $\mathrm{Nm}^{-2}.$

Given below are two statements:

Statement-I: When a capillary tube is dipped into a liquid, the liquid neither rises nor falls in the capillary. The contact angle may be $0^{\circ}.$

Statement-II: The contact angle between a solid and a liquid is a property of the material of the solid and liquid as well.

In the light of above statement, choose the correct answer from the options given below.

The potential energy of molecule on the surface of a liquid compared to one inside the liquid is

An object is floating in a liquid, kept in a container. The container is placed in a lift. Choose the correct option.

When a cylindrical tube is dipped vertically into a liquid the angle of contact is ${140^\mathrm{o}}$, when the tube is dipped with an in inclination of ${40^ \circ }$ the angle of contact is

A rectangular block is $5\mathrm{cm} \times 5\mathrm{cm} \times 10\mathrm{cm}$ in size. The block is floating in water with 5 cm side vertical. If it floats with 10 cm side vertical, what change will occur in the level of water?

Capillaries of length $\ell$ and $2 \ell$ are connected in series. Their radii are $r$ and $2 r$ respectively. If stream line but viscous flow is maintained and pressure difference across first and second capillaries are ${P}_1$ and ${P}_2$ respectively. Then the ratio $\frac{P_1}{P_2}$ will be

Statement A: A needle placed carefully on the surface of water may float, whereas a ball of the same material will always sinks.
Statement B: The buoyancy of an object depends both on the material and shape of the object.

A liquid does not wet the sides of a solid, if the angle of contact is