ISC Physics Class XI Part 1>Chapter 17 - Motion in Fluids : Viscosity>FOR DIFFERENT COMPETITIVE EXAMINATIONS>Q 16

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Two solid spheres $A$ and $B$ of equal volumes but of different densities $d_{A}$ and $d_{B}$ are connected by a string. They are fully immersed in a fluid of density $d_{F}$ . They get arranged into an equilibrium state as shown in the figure with a tension in the string. The arrangement is possible only if:

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Important Questions on Motion in Fluids : Viscosity

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ISC Physics Class XI Part 1>Chapter 17 - Motion in Fluids : Viscosity>FOR DIFFERENT COMPETITIVE EXAMINATIONS>Q 17

People living in houses far away from the municipal tank often find it difficult to get water on the top floor even if it is situated at lower level than the level of water in the tank. The reason for this is:

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ISC Physics Class XI Part 1>Chapter 17 - Motion in Fluids : Viscosity>FOR DIFFERENT COMPETITIVE EXAMINATIONS>Q 18

The velocity of falling raindrops attains a limiting value, because of:

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ISC Physics Class XI Part 1>Chapter 17 - Motion in Fluids : Viscosity>FOR DIFFERENT COMPETITIVE EXAMINATIONS>Q 19

A small lead ball is falling freely in a viscous liquid. The velocity of the ball:

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ISC Physics Class XI Part 1>Chapter 17 - Motion in Fluids : Viscosity>FOR DIFFERENT COMPETITIVE EXAMINATIONS>Q 20

A small spherical solid ball is dropped in a viscous liquid. Its journey in the liquid is best described in the figure by:

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ISC Physics Class XI Part 1>Chapter 17 - Motion in Fluids : Viscosity>FOR DIFFERENT COMPETITIVE EXAMINATIONS>Q 21

If the terminal speed of a sphere of gold ( density

= 19.5 k g m^{- 3}

) is

0.2 m s^{- 1}

in a viscous liquid (density

= 10.5 k g m^{- 3}

). Find the terminal speed of a sphere of silver (density

= 10.5 k g m^{- 3}

) of the same size in the same liquid:

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ISC Physics Class XI Part 1>Chapter 17 - Motion in Fluids : Viscosity>FOR DIFFERENT COMPETITIVE EXAMINATIONS>Q 22

Spherical balls of radius

r

Are falling in a viscous fluid of viscosity

η

with a velocity

v

. The retarding viscous force acting on the spherical ball is:

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ISC Physics Class XI Part 1>Chapter 17 - Motion in Fluids : Viscosity>FOR DIFFERENT COMPETITIVE EXAMINATIONS>Q 23

The terminal velocity

v

of a small sphere of radius

r

falling through a viscous liquid varies with

r

such that:

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ISC Physics Class XI Part 1>Chapter 17 - Motion in Fluids : Viscosity>FOR DIFFERENT COMPETITIVE EXAMINATIONS>Q 24

A spherical solid ball of volume

V

is made of a material of density

ρ_{1}

. It is falling through a liquid of density

ρ_{2} (ρ_{2} < ρ_{1})

. Assume that the liquid applies a viscous force on the ball that is proportional to the square of its speed

v

that is

F_{v i s c o u s} = - k v^{2} (k > 0)

. The terminal speed of the ball is: