Mechanical properties of fluids practice · Mixed difficulty

Reynolds number is the ratio of:

A metal plate of area ${10^3}\mathrm{c}{\mathrm{m}^2}$ rests on a layer of oil 6 mm. thick. A tangential force of ${10^{ - 2}}\mathrm{N}$ is applied on it to move it with a constant velocity of $6\mathrm{cm}{\mathrm{s}^{ - 1}}$. The coefficient of viscosity of the liquid is

Assertion: A thin stainless steel needle can lay floating on a still water surface.
Reason: Any object floats when the buoyancy force balances the weight of the object.

The surface energy of liquid film on a ring of area $0.15\,{m^2}$ is (T=5 N/m)

The pressure at the bottom of a tank containing a liquid does not depend on

Assertion: If an object is submerged in fluid at rest, the fluid exerts a force on its surface.
Reason: Force exerted by the fluid at rest has to be parallel to the surface in contact with it.

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

A body measures $5 \mathrm{~N}$ in air and $2 \mathrm{~N}$ when put in water. The buoyant force is

Which among the following is incorrect?

A: A hydrogen filled balloon stops raising after it has attained a certain height in the sky
R: The buoyancy of an object depends both on the material and shape of the object

A swimmer goes the surface of water to a depth of 20 m, the change in the pressure on his body is nearly

If Reynold's number is greater than 3000, the flow of liquid is:

Two identical spherical soap bubbles collapses. If $V$ is the consequent change in volume of the contained air, $S$ is the change in the total surface area and $T$ is the surface tension of the soap solution, then (if $p_0$ is atmospheric pressure and assume temperature to remain same in all the bubbles).

A film of water is found between two straight parallel wires of length 10 cm each separated by 0.2 cm. If their separation is increased by 1 mm, while still maintaining their parallelism, how much work will have to be done? (surface tension of water is $7.2 \times {10^{ - 2}}\mathrm{N}{\mathrm{m}^{ - 1}}$)

A wooden cube floating in water supports a mass of $m=0.2 {~kg}$ on its top. When the mass is removed, the cube rises by $2 {~cm}$. The side of the cube is $\left(\rho_{\text {water }}\right.$ $=10^3 {~kg} / {m}^3$ )

Assuming that the atmosphere has the same density anywhere as at sea level $\left(\rho=1.3 \mathrm{kgm}^{-3}\right)$ and $g$ to be constant $\left(g=10 \mathrm{~ms}^{-2}\right)$. What should be the approximate height of atmosphere? $\left(p_0=1.01 \times 10^5 \mathrm{Nm}^{-2}\right)$

The glycerin of density $1.25 \times {10^3}\;\mathrm{kg}{\mathrm{m}^{ - 3}}$  is flowing through a conical tube with end radii 0.1 m and 0.04 m respectively. The pressure difference across the ends is $10\mathrm{N}{\mathrm{m}^{ - 2}}$. The rate of flow of glycerine through the tube is

One end of a uniform glass capillary tube of radius$r = 0.025\mathrm{cm}$ is immersed vertically in water to a depth $h = 1\mathrm{cm}$. The excess pressure in $\mathrm{N}{\mathrm{m}^{ - 2}}$ required to blow an air bubble out of the tube (Surface tension of water = $7 \times {10^{ - 2}}\mathrm{N}{\mathrm{m}^{ - 1}}$, Density of water = ${10^3}\mathrm{kg}{\mathrm{m}^{ - 3}}$ , Acceleration due to gravity= 10$\mathrm{m}{\mathrm{s}^{ - 2}}$

The profile of advancing liquid in a tube is a

Spherical ball of radius $R$ are falling in a viscous fluid of viscosity ɳ with a velocity $v$. The retarding viscous force acting on the spherical ball is

A small tiny lead shot is gently dropped on the surface of a viscous liquid

The pressure at the bottom of water tank is 3P, where P is atmospheric pressure. If water is drawn out till the water level decreases by $\frac{2}{5}th$ of initial value then pressure at the bottom of the tank will be

An atmosphere,

With the increase in temperature, the angle of contact

If a soap bubble expands, the pressure inside the bubble:

Two spherical bubbles are in contact with each other internally as shown. The radius of curvature of the common surface is R, then -

Two soap bubbles $A$ and $B$ are formed at the two open ends of a tube. The bubble $A$ is smaller than bubble$B$. Valve and air can flow freely between the bubbles, then

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

The cross sections of a pipe at two points A and B are in the ratio 1:4. If the speed of water flowing through the pipe at point A is V, its speed at point B is

The excess pressure inside one soap bubble is three times that inside a second soap bubble, then the ratio of their surface areas is