Tag: properties of matter

Questions Related to properties of matter

Viscous force a is similar to friction in solids ,but viscous force
a. is independent of area but friction depends on area
b. is temperature dependent while friction force between solids depends upon normal reaction
c. is velocity dependent while friction is velocity independent

viscosity option b: engineering physics properties of matter physics

  1. a, b, c are correct

  2. a, c are correct

  3. b, c are correct

  4. a, b are correct

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Correct Option: C
Explanation:

Viscosity depends of mass of body, temperature, velocity and density.
Where as friction depends only on normal reaction.

The viscous force on a small sphere of radius $R$ moving in a fluid varies as 

viscosity option b: engineering physics properties of matter physics

  1. $\propto \ R^2$

  2. $\propto \ R$

  3. $\propto \ (\dfrac{1}{R})$

  4. $\propto \ (\dfrac{1}{R})^2$

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Correct Option: B

Why does the cotton wick in an oil filled lamp keep on burning?

viscosity option b: engineering physics properties of matter physics

  1. By friction

  2. By capillary action

  3. By electrostatic force

  4. By Gravitational force

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Correct Option: B
Explanation:

Due to surface tension of oil capillary rise can be seen in cotton wick which makes lamp to burn.

When a ball is released from rest in a very long column of viscous liquid, its down ward acceleration is $a'$ (just after released). Its acceleration when it has acquired to third of the maximum velocity is $a/X$. Find the value of $X$.

viscosity option b: engineering physics properties of matter physics

  1. $2$

  2. $3$

  3. $23$

  4. $5$

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Correct Option: B

A liquid rises in a capillary tube when the angle of contact is:

viscosity option b: engineering physics properties of matter physics

  1. $An\ acute\ one$

  2. $An\ obtuse\ one$

  3. $\pi/2\ radian$

  4. $\pi\ radian$

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Correct Option: A
Explanation:

If angle of contact is acute, liquid rises in a capillary tube whereas if angle of contact is obtuse, liquid is depressed in a capillary tube.

Hence, option A is correct.

Two solid metal balls of radii $r$ $2r$ are falling with their terminal speeds in a viscous liquid.What is the ratio of drag force acting on these two balls?

viscosity option b: engineering physics properties of matter physics

  1. 1;2

  2. 1;4

  3. 1;8

  4. 4;1

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Correct Option: C

We have three beakers A, B and C containing glycerine, water and kerosene respectively. They are stirred vigorously and placed on the table. The liquid which comes to rest at the earliest is

viscosity option b: engineering physics properties of matter physics

  1. Glycerine

  2. Water

  3. Kerosene

  4. All of them at the same time

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Correct Option: A

When $200 ml$ of water is subjected to a pressure of $2 \times {10^8}pa,$ the decrease in its volume is $0.2 ml.$ the compressibility of water is -----

viscosity option b: engineering physics properties of matter physics

  1. $5 \times {10^{ - 8}}{m^2}{N^{ - 1}}$

  2. $5 \times {10^{ - 10}}{m^2}{N^{ - 1}}$

  3. $5 \times {10^{ - 12}}{m^2}{N^{ - 1}}$

  4. $None$

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Correct Option: C

A water hose 2 cm in diameter is used to fill a 20 litre bucket. If it takes 1 minute to fill bucket with watch velocity it leaves the hose ,

viscosity option b: engineering physics properties of matter physics

  1. 150 cm/s

  2. 70 cm/s

  3. 106 cm/s

  4. 100 cm/s

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Correct Option: C
Explanation:

Given,

Area, $A=\dfrac{\pi {{d}^{2}}}{4}=\dfrac{\pi }{4}{{\left( 0.02 \right)}^{2}}$

Volume rate of flow, $\dot{V}=\dfrac{volume}{time}=\dfrac{20\,L}{60}=\dfrac{{{10}^{-3}}}{3}\,{{m}^{3}}{{s}^{-1}}$

Volume rate of flow = Cross-Section Area x Velocity of Flow

$ \dot{V}=Av $

$v=\dfrac{{\dot{V}}}{A}=\dfrac{{{10}^{-3}}}{3}\times \dfrac{4}{\pi {{\left( 0.02 \right)}^{2}}}=1.06\,m{{s}^{-1}}=106\,cm{{s}^{-1}}$

Hence, velocity of water leaves hose is$106\,cm{{s}^{-1}}$.

An air bubble of diameter 2mm rises steadily througha solution of density $1750 kg/m^3$at the rate of $0.35cm/s$.Calculate the coefficient of viscosity of the solution.The density of air is negligible. 

viscosity option b: engineering physics properties of matter physics

  1. 10

  2. 11

  3. 12

  4. 13

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Correct Option: B
Explanation:

The force of buoyancy B is equal to the weight of  the displaced liquid. Thus

$\Rightarrow B=\dfrac{4}{3}\pi r^36g$
This force is upward. The viscous force acting downward is $F=6\pi nrv$
The weight of the air bubble may be neglected as the density of air is small. for uniform velocity -
$\Rightarrow F=B$
$\Rightarrow 6\pi nrv=\dfrac{4}{3}\pi r^3 6g$
$\Rightarrow n=\dfrac{2r^36g}{9v}$
         $=\dfrac{2\times \left( 1\times 106{-3}m\right)^2\times \left( 1750kg/m^3\right)\times 9.8m/s^2}{9\times 0.35\times 10^{-2}m/s}$
         $=11\;poise$
This appears to be a highly viscous liquid.