Viscosity

Q.

What is the difference between viscous and non-viscous fluid?

Q.

A uniform half-meter rule balances horizontally on a knife-edge at the 29 cm mark when a weight of 20 gf is suspended from one end.

What is the weight of the half-meter rule?

Q.

What do we mean by 'streamlined shape'? How does it help in the motion of vehicles?

Q.

What is the limit between a perfect fluid and a real fluid?

Q.

Why are ships and boats are made of streamlined?

Q. Why objects moving in fluids must have streamlined shape ?

Q.

Two liquids of densities $D_1$ and $D_2$ are flowing in identical capillary tubes under the same pressure difference. If $T_1$ and $T_2$ are the time taken for the flow of equal quantities (Mass) of liquids. What will be the ratio of the coefficient of viscosity of liquids?

Q. A mixture of NaI and NaCl on reaction with H2SO4 gave Na2SO4 equal to weight if original mixture taken.The percentage of NaI in the mixture is

Q.

In the case of streamlined flow of liquid, the loss of energy is

Q.

For an ideal fluid, viscosity is

1. Unity

2. Zero

3. Infinity

4. Finite but small

Q.

Is there friction between us and the air ?

Q.

Explain why objects moving in fluids must have a special shape ?

Q.

What is terminal velocity?

Q. Assertion : Water flows faster than honey.
Reason: The coefficient of viscosity of water is less than honey.

1. Both assertion and reason are true and reason is correct explanation of assertion.
2. Both assertion and reason are true but reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Q. Which of the following substances has the greatest viscosity?

1. Water
2. Mercury
3. Keroscene
4. Glycerine

Q.

The quantity which decides the nature of the flow of a viscous liquid through a pipe is known as

Q. Question 16

A gas filled balloon moves up. Is the upward force acting on it larger or smaller than the force of gravity?

Q. A good lubricant must have:

1. low viscosity
2. high viscosity
3. high density
4. low surface tension

Q. Assertion :A helium filled balloon does not rise indefinately in air but halts after a certain height. Reason: Viscosity opposes the motion of balloon

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Q. Why did the stone & feather falls in a same rate of acceleration, on sucking the air in the gas jar ?

Q. The velocity of falling rain drop attain limited value because of:

1. Surface tension
2. Upthrust due to air
3. Viscous force exerted by air
4. Air current

Q. Viscosity decreases with increase in temperature is the reason for
(i) Hot water moving faster than cold water
(ii) More viscous oils are used in motor cars during summer than in winter.

1. Only (i) is correct
2. Both (i) and (ii) are correct
3. Only (ii) correct
4. Both are wrong

Q. The force which resists motion in a liquid is called___.

Q. More viscous oil is used in summer than in winter in motors due to

1. rise in temperature in summer, the viscosity of oil increases.
2. surface tension of oil increases.
3. rise in temperature in summer, the viscosity of oil decreases.
4. surface tension of oil decreases.

Q.

Liquids offer more friction than the gases.

1. True
2. False

Q. The velocity of falling rain drops attains limited value because of :

1. air current
2. surface tension
3. upthrust due to air
4. viscous force exerted by air

Q. Assertion: Machine parts are jammed in winter.
Reason: The viscosity of lubricant used in machine parts increase at low temperatures

1. If both assertion and reason are true but the reason is the correct explanation of assertion.
2. If both assertion and reason are true but the reason is not the correct explanation of assertion.
3. If assertion is true but reason is false.
4. If both the assertion and reason are false.
5. If reason is true but assertion is false.

Q. A cubical block of side '$a$' and density '$\rho$' slides over a fixed inclined plane with constant velocity '$v$'. There is a thin film of viscous fluid of thickness '$t$' between the plane and the block. Then the coefficient of viscosity of the thin film will be (Acceleration due to gravity is $g$):

1. $\eta =\frac{\rho agt\sin \theta }{V}$
2. $\frac{\rho ag{t}^2\sin \theta }{V}$
3. $\frac{V}{\rho agt\sin \theta }$
4. none of these

Q. The quality of fountain-pen ink depends largely on:

1. Surface tension of the liquid
2. Viscosity of ink
3. impurities in ink
4. Density of ink

Q.

Explain why objects moving in fluids must have a special shape?