HARD

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An earthen pitcher loses $1 g$ of water per minute due to evaporation. If the water equivalent of pitcher is $0.5 kg$ and the pitcher contains $9.5 kg$ of water, calculate the time required for the water in the pitcher to cool to $28 ° C$ from its original temperature of $30 ° C$ . Neglect radiation effects. Latent heat of vapourization of water in this range of temperature is $580 cal g^{- 1}$ and specific heat of water is $1 kcal {kg}^{- 1} ° C^{- 1}$ .

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Important Questions on Thermal Properties of Matter

MEDIUM

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

Steam at

100^{o} C

is passed into

20 g

of water at

10^{o} C .

When water acquires a temperature of

80^{o} C,

the mass of water present will be:
[Take specific heat of water

= 1 c a l g^{- 1 o} C^{- 1}

and latent heat of steam

= 540 c a l g^{- 1}]

EASY

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

Heat required to melt $1 g$ of ice is $80 cal$ . A man melts $60 g$ of ice by chewing in one minute. His power is______

EASY

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

In an experiment, a sphere of aluminium of mass

0.20 kg

is heated up to

150 ° C

. Immediately, it is put into water of volume

150 cc

27^{o} C

kept in a calorimeter of water equivalent to

0.025 kg

. The final temperature of the system is

40^{o} C

. The specific heat of the aluminium is(take

4.2 Joule = 1 calorie

)

EASY

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

Two systems are in thermal equilibrium. The quantity which is common for them is

EASY

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

The quantities of heat required to raise the temperature of two solid copper spheres of radii

r_{1}

and

r_{2} (r_{1} = 1.5 r_{2})

through

1 K

are in the ratio:

MEDIUM

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

50 g

of ice at

0 ° C

is mixed with

50 g

of water at

80 ° C

. If the latent heat of ice is

80 cal g^{- 1}

and specific heat of water is

1 cal g^{- 1} ° C^{- 1}

, then the final temperature of mixture is

EASY

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

A steam engine intakes $50 g$ of steam at $100 ° C$ per minute and cools it down to $20 ° C$ . If latent heat of vaporization of steam is $540 cal g^{- 1}$ , then the heat rejected by the steam engine per minute is _____ $\times 10^{3} cal$

(Given : specific heat capacity of water : $1 cal g^{- 1} {{}^{\circ}C}^{- 1}$ )

MEDIUM

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

A solid metal weighing

150 g

melts at its melting point of

800 ° C

by providing heat at the rate of

100 W

. The time taken for it to completely melt at the same temperature is

4 \min

. What is the specific latent heat of fusion of the metal?

EASY

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

Latent heat of vaporisation of water is

22.6 \times 10^{5} J {kg}^{- 1}

. The amount of heat needed to convert

100 kg

of water into vapour at

100 ° C

HARD

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

A thermally insulated cubical box of side length $20 cm$ and wall thickness $2 cm$ containing $2 kg$ of ice is closed on all sides. The mass of ice melted in $10$ hours is (Thermal conductivity of the material of the box $= 0.01 {Wm}^{- 1} K^{- 1},$ latent heat of ice $= 360 \times 10^{3} J {kg}^{- 1}$ and ambient temperature $= 40 ° C$ )

EASY

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

If pressure increased on a piece of wax, the melting point of wax

MEDIUM

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

A thermally insulated vessel contains

150 g

of water at

0 ° C

. Then the air from the vessel is pumped out adiabatically. A fraction of water turns into ice and the rest evaporates at

0 ° C

itself. The mass of evaporated water will be closest to: (Latent heat of vaporization of water

= 2.10 \times 10^{6} J k g^{- 1}

and Latent heat of Fusion of water

= 3.36 \times 10^{5} J k g^{- 1}

)

EASY

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

The physical quantity that determines whether or not a given system

A

is in thermal equilibrium with another system

B

is called

EASY

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

A closed bottle containing water at

30^{o} C

is open on the surface of the moon. Then-

HARD

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

Explain the following temperature versus time graph:

Question Image

MEDIUM

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

An experiment takes

10 \min

to raise the temperature of water in a container from

0^{o} C

100^{o} C

and another

55 \min

to convert it totally into steam by a heater supplying heat at a uniform rate. Neglecting the specific heat of the container and taking specific heat of the water to be

1 cal {(g^{\circ} C)}^{- 1}

, the heat of vaporization according to this experiment will come out to be:

HARD

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

A water cooler of storage capacity

120

litres can cool water at constant rate of

P

W

. In a closed circulation system (as shown schematically in the figure), the water from the cooler is used to cool an external device that generates constantly

3

kW

of heat (thermal load). The temperature of water fed into the device can not exceed

30^{o} C

and the entire stored

120

litres of water is initially cooled to

10^{o} C

. The entire system is thermally insulated. The minimum value of

P

(in

W

) for which the device can be operated for

3

hours is:

(Specific heat of water is

4.2 kJ

k g^{- 1} K^{- 1}

and the density of water is

1000 kg m^{- 3}

)

HARD

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

10 H

inductor carries a current of

20 A

. If the energy stored in this inductor melts ice at

0 ° C,

then the mass of the ice melted is

[

Latent heat of ice

= 2.26 \times 10^{3} J {kg}^{- 1}]

MEDIUM

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

1 kg

of water, at

20 ° C

is heated in an electric kettle whose heating element has a mean (temperature averaged) resistance of

20 Ω .

The rms voltage in the mains is

200 V

. Ignoring heat loss from the kettle, time taken for water to evaporate fully is close to
[ Specific heat of water

= 4200 J {kg}^{- 1} ° C^{- 1}

Latent heat of water

= 2260 k J k g^{- 1}

]

EASY

Physics>Heat and Thermodynamics>Thermal Properties of Matter>Change of State

A piece of ice falls from a height

h

so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The value of

h

is:
(Latent heat of ice is

3.4 \times 10^{5} {J kg}^{- 1}

and

g = 10 {N kg}^{- 1}

)

Important Questions on Thermal Properties of Matter

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