EASY

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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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Important Questions on Fluid Dynamics

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

The velocity of upper layer of water in a river is

36 km h^{- 1}

. Shearing stress between horizontal layers of water is

10^{- 3} N m^{- 2}

. Depth of the river is _____

m

. (Co-efficient of viscosity of water is

10^{- 2} Pa s

)

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

A flat plate of area $10 {cm}^{2}$ is separated form a large plate by a layer of Glycerine $1 mm$ thick. If the coefficient of viscosity of Glycerine is $20$ poise, the force required to keep the plate moving with a velocity of $1 cm s^{- 1}$ is

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

p

is the density and

η

is coefficient of viscosity of fluid which flows with a speed

v

in the pipe of diameter

d

, the correct formula for Reynolds number

R_{e}

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

Two rain drops falling through air have radii in the ratio

1 : 2

. They will have terminal velocity in the ratio

MEDIUM

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

A solid sphere of volume

V

experiences a viscous force

F

when descending with a speed

v

in a liquid. If another solid sphere of volume

27 V

descends with the same speed

v

in the same liquid, it experiences a viscous force

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

In an experiment to verify Stokes law, a small spherical ball of radius

r

and density

ρ

falls under gravity through a distance

h

in air before entering a tank of water. If the terminal velocity of the ball inside water is same as its velocity just before entering the water surface, then the value of

h

is proportional to: (ignore viscosity of air)

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

Oil is used for frying food materials rather than water, since oil

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

An air bubble of radius

1.0 cm

rises with a constant speed of

3.5 mm s^{- 1}

through a liquid of density

1.75 \times 10^{3} kg m^{- 3} .

Neglecting the density of air. the coefficient of viscosity of the liquid is _________

{kgm}^{- 1} s^{- 1}

HARD

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

A steel ball is dropped in a viscous liquid. The distance of the steel ball from the top of the liquid is shown below. The terminal velocity of the ball is closest to

Question Image

MEDIUM

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

The velocity of a small ball of mass

M

and density

ρ

, when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is

\frac{ρ}{2}

, then the viscous force acting on the ball will be:

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

A small spherical body of radius $r$ and density $ρ$ moves with the terminal velocity $v$ in a fluid of coefficient of viscosity $η$ and density $σ .$ What will be the net force on the body?

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

The velocity of water in a river is

18 km h^{- 1}

near the surface. If the river is

5 m

deep, find the shearing stress between the horizontal layers of water. The coefficient of viscosity of water

= 10^{- 2} poise

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

The velocity of rain drop having radius

1 mm

20 cm s^{- 1}

. The velocity of raindrops of size

3 mm

MEDIUM

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

The velocity of water in a river is

18 km h^{- 1}

near the surface. If the river is

5 m

deep, find the shearing stress between the horizontal layers of water. The coefficient of

viscosity of water = 10^{- 2} poise

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

Under a constant pressure head, the rate of flow of orderly volume flow of liquid through a capillary tube is

V .

if the length of the capillary is doubled and the diameter of the bore is halved, the rate of flow would become

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

Two rain drops falling through air have radii in the ratio

1 : 2

. They will have terminal velocity in the ratio________

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

What is the terminal velocity of air bubble of

1.0 mm

in diameter rising in liquid of viscosity

0.85 N - s m^{- 2}

and density

900 kg m^{- 3}

?(air density

1.293 kg m^{- 3}, g = 9 m s^{- 2}]

EASY

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

Identify the incorrect statement regarding Reynold's number

(R_{e}) :

HARD

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

Water from a pipe is coming at a rate of

100

liters per minute. If the radius of the pipe is

5 c m,

the Reynolds number for the flow is of the order of: (density of water =

100 k g / m^{3},

coefficient of viscosity of water

= 1 m P a s)

MEDIUM

Physics>Mechanical Properties of Matter>Fluid Dynamics>Viscosity

If it takes 5 minutes to fill a 15 litre bucket from a water tap of diameter

\frac{2}{\sqrt{π}} c m

then the Reynolds number for the flow is (density of water =

10^{3} k g / m^{3} a n d v i s c o s i t y o f w a t e r = 10^{- 3} P a . s

) close to:

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

Important Questions on Fluid Dynamics

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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