Question 1

If two bodies are in thermal equilibrium in one frame, will they be in thermal equilibrium in all frames?

Accepted Answer

If two bodies are in thermal equilibrium in one frame, they will be in thermal equilibrium in all the frames. In case there is any change in temperature of one body due to change in frame, the same change will be acquired by the other body.

Question 2

Does the temperature of a body depend on the frame from which it is observed?

Accepted Answer

No, the temperature of a body is not dependent on the frame from which it is observed. This is because atoms /molecules of matter move or vibrate in all possible directions. Increase in velocity at a particular direction of the container/ matter does not increase or decrease the overall velocity of the molecules/atoms because of the random collisions the entities suffer. So, there is no net rise in temperature of the system.

Question 3

It is said that mercury is used in defining the temperature scale because it expands uniformly with  temperature. If the temperature scale is not yet defined, is it logical to say that a substance expands uniformly with temperature?

Accepted Answer

It is not illogical to say that mercury expands uniformly before temperature scale was defined. It's uniform expansion can be studied by comparing the expansion of mercury with expansion of other substances (like alcohol water etc).

Question 4

In defining the ideal gas temperature scale, it is assumed that the pressure of the gas at constant volume is proportional to the temperature T. How can we verify whether this is true or not? Do we have to apply the kinetic theory of gases? Do we have to depend on experimental result that the pressure is proportional to temperature?

Accepted Answer

The ideal gas thermometer is based on the ideal gas equation, PV=nRT, where P is pressure of the gas at constant volume V with n number of moles at temperature T. Therefore, P = constant × T. According to this relation, if the volume of the gas used is constant, the pressure will be directly proportional to the temperature of the gas. We need not use kinetic theory of gases or any experimental results.

Question 5

Can the bulb of a thermometer be made of an adiabatic wall?

Accepted Answer

The bulb of a thermometer plays an important role in measuring the temperature of the surrounding body.  It is put in contact with the body whose temperature is to be measured. The bulb attains the temperature of the body, which allows calibration of temperature. If the bulb is made of an adiabatic wall, then no heat will be transferred through the wall and the bulb cannot attain thermal equilibrium with the surrounding body. Therefore, the bulb cannot be made of an adiabatic wall.

Question 6

Why do marine animals live deep inside a lake when the surface of the lake freezes?

Accepted Answer

Water possesses an anomalous behavour. The volume of a given amount of water decreases as it is cooled from room temperature, until its temperature reaches 4∘C . Below 4∘C , the volume increases, and therefore the density decreases.When the temperature of the surface of lake falls in winter, the water at the surface becomes denser and sinks. As, the temperature reaches below 4∘C , the density of the water at surface becomes less. Thus, it remains at surface and freezes. As, the ice is a bad conductor of heat, it traps the heat present in the lake's water beneath itself. Hence, no further cooling of water takes place once the top layer of the lake is completely covered by ice. Thus the life of the marine animals inside the lake is possible.

Question 7

The length of a brass rod is found to be less on a hot summer day than on a cold winter day as measured by the same aluminium scale. Can we conclude that brass shrinks on heating?

Accepted Answer

On a hot summer day, metals tend to expand due to the heat. Different metals have different expansion coefficients. The coefficient of linear expansion of aluminium is more than that of brass. Therefore, it'll expand more than brass, leading to an apparent decrease in length of the brass rod, as measured by the aluminium scale. So, we cannot conclude that brass shrinks on heating. Instead, aluminium expands more than brass on heating.

Question 8

If mercury and glass had equal coefficients of volume expansion, could we make a mercury thermometer in a glass tube?

Accepted Answer

Yes, we can make a mercury thermometer in a glass tube. Mercury and glass have equal coefficients of volume expansion. So, when temperature changes, the increase in the volume of the glass tube as which is equal to the real increase in volume minus the increase in the volume of the container, would be zero. Hence, it will give correct reading at every temperature.

Question 9

The density of water at 4°C is supposed to be 1000 kg m–3 . Is it same at sea level and at high altitude?

Accepted Answer

At sea level, the pressure is around 1 atmosphere and at high altitude, the density of air reduces.Pressure of liquid,P=hρg where ρ=  density of fluidThe above equation shows that pressure depends on density. Therefore at 4∘C , the density of water will be less at high altitude, compared to the density at sea level.

Question 10

A tightly closed metal lid of a glass bottle can be opened more easily if it is put in hot water for some time. Explain.

Accepted Answer

When a bottle with a tightly-closed metal lid is put in hot water for sometime, its lid can be opened easily because metals have greater coefficient of expansion than glass. Therefore, when the metal lid comes in contact with hot water, it'll expand more than the glass container. As a result, it will be easier to open the bottle.

Question 11

If an automobile engine is overheated, it is cooled by pouring water on it. It is advised that the water should be poured slowly with the engine running. Explain the reason.

Accepted Answer

In a hot engine the hot parts are expanded because of heat, if cold water is poured suddenly then there will be uneven thermal contraction in the parts. This will result in a stress to develop between the various parts of the engine and may let the engine to crack down.

Question 12

Is it possible for two bodies to be in thermal equilibrium if they are not in contact?

Accepted Answer

Two bodies are said to be in thermal equilibrium if they are at the same temperature. Consider two bodies A and B that are not in contact with each other but in contact with a heat reservoir. Since both the bodies will attain the temperature of the reservoir, they will be at the same temperature and, hence, in thermal equilibrium. Therefore, it is possible to have two bodies in thermal equilibrium even though they are not in contact.

Question 13

A spherical shell is heated. The volume changes according to the equation Vθ​=V0​(1+γθ​). Does the volume refer to the volume enclosed by the shell or the volume of the material making up the shell?

Accepted Answer

When a spherical shell is heated, its volume changes according to the equation, Vθ​=V0​(1+γΔθ) . The volume referred to here is the volume of the material used to make up the shell, as its volume expands with the rise of temperature with coefficient of expansion of volume, γ .

Question 14

A system X is neither in thermal equilibrium with Y nor with Z. The systems Y and Z:

Accepted Answer

(c)May be in thermal equilibrium.The given data in the question is insufficient to specify the relation between the physical conditions of systems Y and Z. As  system X is not in thermal equilibrium with Y and Z, systems Y and Z may be at the same temperature or they may or may not be in thermal equilibrium with each other.

Question 15

Which of the curves in the following figure represents the relation between Celsius and Fahrenheit temperatures?

Accepted Answer

The correct option is (a).Celsius and Fahrenheit temperatures are related in the following way:C=95​F−9160​ Here, F=  temperature in FahrenheitC=  temperature in CelsiusIf this equation is plotted on the graph, then the curve will be represented by curve 'a' lying in the fourth quadrant with slope 5/9.  So, the correct option is (a).

Question 16

Which of the following pairs may give equal numerical values of the temperature of a body?

Accepted Answer

(a) Fahrenheit and KelvinLet θ  be the temperature in Fahrenheit and Kelvin scales.We know that the relation between the temperature in Fahrenheit and Kelvin scales is given by180TF​−32​=100TK​−273.15​TF​=TK​=θ Therefore,180θ−32​=100θ−273.15​5θ−160=9θ−2458.54θ=2298.35θ=574.59∘ If we consider the same for Celsius and Kelvin scales100Tc​−0​=100TK​−273.15​ Let the temperature be t 100t−0​=100t−273.15​t=t−273.15 Thus, t  does not exist.The Kelvin scale uses mercury as thermometric substance, whereas the platinum scale uses platinum as thermometric substance. The scale depends on the properties of the thermometric substance used to define the scale. The platinum and Kelvin scales do not agree with each other. Therefore, there is no such temperature that has same numerical value in the platinum and Kelvin scale.

Question 17

For a constant-volume gas thermometer, one should fill the gas at:

Accepted Answer

High temperature and low pressure. A constant-volume gas thermometer should be filled with an ideal gas in which particles don't interact with each other and are free to move anywhere, so that the thermometer functions properly. An ideal gas is only a theoretical possibility. Therefore, the gas that is filled in the thermometer should be at high temperature and low pressure, as under these conditions, a gas behaves as an ideal gas.

Question 18

Consider the following statements.(A) The coefficient of linear expansion has dimension K−1 .(B) The coefficient of volume expansion has dimension K−1 .

Accepted Answer

(a) A  and B  are correct.The coefficient of linear expansion,α=L1​ΔTΔL​=[LT][L]​=K−1 Here, L=  initial length△L=  change in length△T=  change in temperatureOn the other hand, the coefficient of volume expansion,γ=V1​ΔTΔV​=[L3T][L3]​=K−1 Here, V=  initial volume△V=  change in volume△T=  change in temperature△T=  change in temperature K=  kelvin, the S.I. unit of temperature

Question 19

A metal sheet with a circular hole is heated. The hole:

Accepted Answer

When a metal sheet is heated, it starts expanding and its surface area will start increasing, which will lead to an increase in the radius of the hole. Hence, the circular hole will become larger.

Question 20

Two identical rectangular strips, one of copper and the other of steel, are riveted together to form a bimetallic strip (acopper ​>asteel ​). On heating, this strip will:

Accepted Answer

(c) Bend with copper on convex side.We are provided with two metal strips of copper and steel. On heating, both of them will expand. Expansion coefficient of copper is more than that of steel. So, the copper metal strip will expand more, causing the bimetallic strip to bend with copper at the convex side, as it'll have more surface area compared to the steel sheet, which will be on the concave side.

Filters

Filters

class

subject

topic

concept

difficulty

Solutions for Thermal properties of Matter Important Questions

Found the solution, but did not understand the concept?

Ask my first question