A big drop of radius $R$ is formed from 1000 droplets of water. The radius of a droplet will be
- A$10 \mathrm{R}$
- ✓$\frac{R}{10}$
- C$\frac{R}{100}$
- D$\frac{R}{1000}$
Answer: B.
View full solution →Question types
Mechanical Properties of Fluids question types
253 questions across 5 question groups — pick any mix to generate a Physics paper with step-by-step answer keys.
253
Questions
5
Question groups
5
Question types
01
M.C.Q (1 Marks)
67 Q→02Very Short Answer Type Question
5 Q→03Short Answer Type Question
53 Q→04Answer the following in Brief
62 Q→05Answer the following in Detail
66 Q→Sample Questions
Mechanical Properties of Fluids questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
A matchstick $5 \mathrm{~cm}$ long floats on water. The water film has a surface tension of $70 \mathrm{dyn} / \mathrm{cm}$. A little comphor put on one side of stick reduces the surface tension there to $50 \mathrm{dyn} / \mathrm{cm}$. The net force on the matchstick is
- A4 dynes
- B20 dynes
- ✓100 dynes
- D600 dynes.
Answer: C.
View full solution →A thin ring of diameter $8 \mathrm{~cm}$ is pulled out of water (surface tension $0.07 \mathrm{~N} / \mathrm{m}$ ). The force required to break free the ring from water is
- A$0.0088 \mathrm{~N}$
- B$0.0176 \mathrm{~N}$
- ✓$0.0352 \mathrm{~N}$
- D$3.52 \mathrm{~N}$.
Answer: C.
View full solution →The surface tension acts
- Aperpendicular to the surface and vertically up-wards
- Bperpendicular to the surface and vertically into the liquid
- ✓tangential to the surface
- Donly at the liquid-solid interface.
Answer: C.
View full solution →Rain drops or liquid drops are spherical in shape, especially when small, because
- Acohesive force between the molecules of water have spheres of influence
- ✓for a given volume, a spherical drop has the least surface energy
- Cfor a given volume, a spherical drop has the maximum surface energy
- Dthe pressure inside a drop is many times the atmospheric pressure outside.
Answer: B.
View full solution →What is the basis of the Bernoulli’s principle
Why is the surface tension of paints and lubricating oils kept low?
The figures show three containers filled with the same oil. How will the pressures at the reference compare ?
What happens to surface tension under different gravity (e.g., aboard the International Space Station or on the lunar surface)?
Can you suggest any method to measure the surface tension of a soap solution? Will this method have any commercial application?
You can squirt water a considerably greater distance by placing your thumb over the end of a garden hose. Explain.
Explain why flow speed is greatest where streamlines are closest together.
State the SI unit for volume flow rate.
The relative velocity between two layers of a fluid, separately by $0.1 \mathrm{~mm}$, is $2 \mathrm{~cm} / \mathrm{s}$. Calculate the velocity gradient.
View full solution →Would you rather have someone wearing studs step on your foot or have someone wearing tennis shoes step on your foot?
A liquid is flowing through a horizontal pipe of varying cross section. At a certain point, where the diameter of the pipe is $5 \mathrm{~cm}$, the flow velocity is $0.25 \mathrm{~m} / \mathrm{s}$. What is the flow velocity where the diameter is $1 \mathrm{~cm}$ ?
View full solution →If the speed at which water flows through a long cylindrical pipe of radius $8 \mathrm{~mm}$ is $10 \mathrm{~cm} / \mathrm{s}$, find the Reynolds number. [Density of water $=1 \mathrm{~g} / \mathrm{cm}^3$, coefficient of viscosity of water = 0.01 poise]
View full solution →A spherical liquid drop of diameter $2 \times 10^{-4} \mathrm{~m}$ is falling with a constant velocity through air, under gravity. If the density of the liquid is $500 \mathrm{~kg} / \mathrm{m} 3$ and the coefficient of viscosity of air is $2 \times 10^{-5} \mathrm{~Pa} . \mathrm{s}$, determine the terminal velocity of the drop and the viscous force acting on it. Ignore the density of air.
View full solution →A metal plate of length $10 \mathrm{~cm}$ and breadth $5 \mathrm{~cm}$ is in contact with a layer of oil $1 \mathrm{~mm}$ thick. The horizontal force required to move it with a velocity of $4 \mathrm{~cm} / \mathrm{s}$ along the surface of the oil is $0.32 \mathrm{~N}$. Find the coefficient of viscosity of the oil. Also express it in poise.
View full solution →Calculate the force required to move a flat glass plate of area of $10 \mathrm{~cm}^2$ with a uniform velocity of $1 \mathrm{~cm} / \mathrm{s}$ over the surface of a liquid $2 \mathrm{~mm}$ thick, if the coefficient of viscosity of the liquid is 2 Pa.s.
View full solution →Explain the continuity condition for a flow tube. Show that the flow speed is inversely proportional to the cross-sectional area of a flow tube.
Define mass flow rate or mass flux. Explain how it is related to the velocity of fluid.
Define volume flow rate or volume flux. Explain how it is related to the velocity of fluid. OR
What is the difference between flow rate and fluid velocity? How are they related?
What is the difference between flow rate and fluid velocity? How are they related?
State Stokes' law. Derive Stokes' law using dimensional analysis.
Find the conversion factor between the SI and CGS units of coefficient of viscosity using dimensional analysis.
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