Mechanical properties of fluids practice · Medium

Statement A: Hot soap solution is preferred for washing dirty clothes.
Statement B: Surface tension of soap solution decreases on heating.

A metal ball immersed is alcohol weighs $W_1$ at $0^{\circ} {C}$ and $W_2$ at $50^{\circ} {C}$. Assuming that the density of the metal is large compared to that of alcohol, then

Radius of a soap bubble is 'r', surface tension of soap solution is T. Then without increasing the temperature, how much energy will be needed to double its radius

The pans of a physical balance are in equilibrium. Air is blown under the right hand pan; then the right hand pan will

A steel ball is dropped in oil then,

A: During takeoff of an aeroplane, velocity of air above the wing is greater than velocity below the wing
R: Bernoulli's principle is based on law of conservation of energy

A rain drop of radius $0.3 \mathrm{~mm}$ has a terminal velocity in air $1 \mathrm{~ms}^{-1}$. The viscosity of air is $18 \times 10^{-5}$ poise. Find the viscous force on the rain drops.

A cylindrical vessel of height $500mm$ has an orifice (small hole) at its bottom. The orifice is initially closed and water is filled in it up height $H$. Now the top is completely sealed with a cap and the orifice at the bottom is opened. Some water comes out from the orifice and the water level in the vessel becomes steady with height of water column being $200mm$. Find the fall in height (in $mm$) of water level due to opening of the orifice
(Take atmospheric pressure $= 1.0 \times {10^5}N/{m^2}$, density of water $= 1000kg/{m^3}$ and $g = 10m/{s^2}$. Neglect any effect of surface tension)

If 27 identical liquid drops are combined to form a larger drop of radius $R$, then loss of surface energy is (surface tension of liquid is $S {~N} {~m}^{-1}$ )

Surface tension vanishes at

The excess pressure inside an air bubble of radius $\text{r}$ just below the surface of water is $\text{p}_1.$ The excess pressure inside a drop of the same radius just outside the surface is $\mathrm{p}_2$. If $\mathrm{T}$ is surface tension, then

If two soap bubbles of different radii are connected by a tube. Then

A small sphere of mass m is dropped from a great height. After it has fallen $100m$, it has attained its terminal velocity and continues to fall at that speed. The work done by air friction against the sphere during the first $100m$ of fall is

Three liquids of equal masses are taken in three identical cubical vessels A ,B and C . Their densities are ${\mathrm{\rho }_A},{\mathrm{\rho }_B}\mathrm{and}{\mathrm{\rho }_C}$ respectively but ${\mathrm{\rho }_A} < {\mathrm{\rho }_B} < {\mathrm{\rho }_C}.$ . below the force extract by the liquid on the base of cubical vessel is

Two drops of same radius are falling through air with steady speed $v$. If the two drops coalesce, what would be the terminal speed

A: An ice block with lead short is floating in water. When ice melt completely water level slightly drops.
R: When ice block with less shot is placed in water, volume of displaced water is more then that of the ice block

A cylinder is filled with liquid of density $d$ upto a height $h$. If the cylinder is at rest, then the mean pressure of the walls is

In streamline flow, velocity of liquid at the bottom layer is:

Assertion: When two boats sail parallel in the same direction and close to each other, they are pulled towards each other.
Reason: The viscous drag on a spherical body moving with speed $v$ is proportional to $v$.

The coefficient of viscosity for hot air is

A flow of liquid is streamline, if the Reynolds' number is

Assertion:- Density of Hollow body is always less then the density of substance of equal mass of the body.
Reason:- Volume of Hollow body is greater than the volume of substance of the body. But mass of Hollow body is equal to mass of substance of the body.

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.

There is a small bubble at one end and bigger bubble at other end of a rod. What will happen?

Blood pressure rises in old age due to arteries becoming narrow. This phenomenon could be explained on the basis of

Pressure applied to enclosed fluid is:

Assertion:- Surface tension of liquid decreases with increase in temperature.
Reason:- Cohesive force between liquid molecules increases with increase in the temperature.

The maximum average velocity of water in a tube of diameter $2 \mathrm{~cm}$ so that the flow becomes laminar is: (The viscosity of water is $10^{-3} \mathrm{~Nm}^{-2} \mathrm{~s}^{-1}$)

Statement -(I) Viscosity of gases $>$ viscosity of liquids

Statement -(II) Surface tension of liquid decrease an adding highly insoluble material.

A cylindrical tank has a hole of $1c{m^2}$in its bottom. If the water is allowed to flow into the tank from a tube above it at the rate of $70c{m^3}/\sec$. then the maximum height up to which water can rise in the tank is