HARD

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A bubble has surface tension $S$ . The ideal gas inside the bubble has ratio of specific heats $γ = \frac{5}{3}$ . The bubble is exposed to the atmosphere and it always retains its spherical shape. When the atmospheric pressure is $P_{a 1}$ , the radius of the bubble is found to be $r_{1}$ and the temperature of the enclosed gas is $T_{1}$ . When the atmospheric pressure is $P_{a 2}$ , the radius of the bubble and the temperature of the enclosed gas are $r_{2}$ and $T_{2}$ , respectively. Which of the following statement(s) is(are) correct?

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Important Questions on Properties of Solid and Liquid

EASY

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

Identify the incorrect statement about 'angle of contact':
(a) Angle of contact depends upon the inclination of the solid surface to the liquid surface.
(b) If the angle of contact of a liquid and a solid surface is less than

90 °,

then the liquid spreads on the surface of the solid.
(c) Angle of contact increases with increase in temperature of liquid.
(d) The value of angle of contact for pure water and glass is zero.

MEDIUM

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

A large number of water drops, each of radius

r

, combine to have a drop of radius

R

. If the surface tension is

T

and mechanical equivalent of heat is

J

, the rise in heat energy per unit volume will be:

MEDIUM

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

A soap bubble of the radius

3 cm

is formed inside another soap bubble of radius,

6 cm

. The radius of an equivalent soap bubble that has the same excess pressure as inside the smaller bubble with respect to the atmospheric pressure is____

cm .

EASY

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): Clothes containing oil or grease stains cannot be cleaned by water wash.

Reason (R): Because the angle of contact between the oil/grease and water is obtuse. In light of the above statements, choose the correct answer from the option given below.

EASY

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

A glass capillary tube is of the shape of a truncated cone with an apex angle

α

so that its two ends have cross-sections of different radii. When dipped in water vertically, the water rises in it to a height

h

, where the radius of its cross-section is

b

. If the surface tension of water is

S

, its density is

ρ

, and its contact angle with glass is

θ

, then the value of

h

will be (

g

is the acceleration due to gravity)

Question Image

EASY

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

If a soap bubble expands, the pressure inside the bubble

MEDIUM

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

A boy formed a bubble and a liquid drop form the same soapy water. The pressure difference between inside and outside of the soap bubble is measured to be

100 N / m^{2} .

If the radius of the droplet is half of the radius of the bubble, then the pressure difference between the inside and outside of the droplet is

EASY

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

Two mercury drops (each of radius

r

) merge to form a bigger drop. The surface energy of the bigger drop, if

T

is the surface tension, is

EASY

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

A soap bubble having radius of

1 m m

is blown from a detergent solution having a surface tension of

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

The pressure inside the bubble equals at a point

Z_{0}

below the free surface of water in a container. Taking

g = 10 m s^{- 2},

density of water

= 10^{3} k g m^{- 3},

the value of

Z_{0}

EASY

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

Pressure inside two soap bubbles are

1.01

and

1.02

atmosphere, respectively. The ratio of their volumes is :

MEDIUM

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

A spherical soap bubble of radius

3 cm

is formed inside another spherical soap bubble of radius

6 cm

. If the internal pressure of the smaller bubble of radius

3 cm

in the above system is equal to the internal pressure of the another single soap bubble of radius

r cm

. The value of

r

is _____

HARD

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

If two glass plates have water between them and are separated by very small distance (see figure), it is very difficult to pull them apart. It is because the water in between forms cylindrical surface on the side that gives rise to lower pressure in the water in comparison to atmosphere. If the radius of the cylindrical surface is R and surface tension of water is T then the pressure in water between the plates is lower by:

Question Image

MEDIUM

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

An air bubble of radius

1 mm

is at a depth of

8 cm

below the free surface of a liquid column. If the surface tension and density of the liquid is

0.1 N m^{- 1}

and

2000 kg m^{- 3}

respectively, by what amount is the pressure inside the bubble greater than the atmospheric pressure?
(Take

g = 10 m s^{- 2}

)

EASY

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

A liquid will not wet the surface of a solid, if the angle of contact is

MEDIUM

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

A large number of liquid drops each of radius

r

coalesce to form a single drop of radius

R

. The energy released in the process is converted into kinetic energy of the big drop so formed. The speed of the big drop is (Surface tension of liquid

T

, Density

ρ

)

EASY

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

The radius

R

of the soap bubble is doubled under isothermal condition. If

T

be the surface tension of the soap bubble, the work done in doing so is given by

MEDIUM

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

A thin metal wire of density

ρ

floats on water surface horizontally. If it is NOT to sink in water then maximum radius of wire is proportional to (

T =

surface tension of water,

g =

gravitational acceleration)

EASY

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

Two separate soap bubbles of radii

3 \times 10^{- 3} m

and

2 \times 10^{- 3} m

respectively, formed of same liquid (surface tension

65 \times 10^{- 2} N m^{- 1}

) come together to form a double bubble. The radius of interface of double bubble is

HARD

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

A small soap bubble of radius 4cm is trapped inside another bubble of radius 6cm without any contact. Let

P_{2}

be the pressure inside the inner bubble and

P_{0}

, the pressure outside the outer bubble. Radius of another bubble with pressure difference

P_{2} - P_{0}

between its inside and outside would be:

MEDIUM

Physics>Mechanics>Properties of Solid and Liquid>Surface Energy and Surface Tension

A soap bubble, blown by a mechanical pump at the mouth of a tube increases in volume with time at a constant rate. The graph that correctly depicts the time dependence of pressure inside the bubble is given by:

Important Questions on Properties of Solid and Liquid

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