Matric Part 1/9th Class Physics Chapter 8 Long Question With Answer for Unit 8 Thermal Properties of Matter

Question # 1

Explain the temperature , heat , thermal equilibrium and internal energy

Ans 1: Temperature: temperature of a body is the degree of hotness or coldness of the body
Ans 2: Heat; heat is the energy that is transferred from one body to the other in thermal contact with each other as a result of the difference of temperature between them.
Explanation: a candle flame is hot and is said to be at high temperature. Ice on the other hand is cold and is said to be at low temperature. Our sense of touch is a simple way to know how much hot or cold a body is. To store ice in summer , people wrap it with cloth or keep it in wooden box in the thermos flask. In this way, the avoid the thermal contract of ice with its hot surrounding otherwise will soon melt away. Similarly, when you place a cup of tea or water in a room, it cools down gradually. It stops cooing as it reaches the room temperature. Thus, a temperature determines the direction of flow of heat. Heat flows from a hot body to a cold body until thermal equilibrium is reached . Take two bodies having different temperatures. bring them in contact with each other . The temperature of the hot body falls. It loose energy. This energy enters the cold body at lower temperature. Cold body gains energy and its temperature rises. The transfer of energy continues till both the bodies have same temperature . The form of energy that is transferred from a hot body to a cold body is called heat.
Ans 3: Thermal equilibrium: the property of a system when all parts of the system have the same temperature along with its surroundings.
Ans 4: Internal energy; the sum of kinetic and potential energy associated with the atoms , molecules and particels of a body is called its internal energy
Ans 5: Dependence; internal energy of a body depends on many factors such as the mas of the body, kinetic and potential energies of molecules etc. Kinetic energy of an atom or molecules is due to its motion which depends upon the temperature. Potential energy of atom or molecules is the stored energy due to its intermolecular forces

Question # 2

What is bimetal strip ? explain and write its uses

Ans 1: Bimetal strip: a bimetal strip consists of two thin strips of different metals such as brass and iron joined together. On heating the strip , brass expands more than iron. This unequal expansion causes bending of strip.
Ans 2: Uses; bimetal strip are used for various purposes. bimetal thermometers are used to measure temperature especially in furnaces and ovens. Bimetal strips are also used in thermostats. Bimetal thermostat switch is used to control the temperature of heater coil in an electric iron.

Question # 3

Define latent heat of fusion and explain it

Ans 1: Latent heat of fusion: heat energy required to change unit mass of a substance from solid to liquid state at its melting point without change in its temperature is called its latent heat of fusion. It is denoted by Hf.
Ice changes at 0C into water. latent heat of fusion of ice is 3.36*105JKg-1. That is 3.36*105 joule heat is required to melt 1 kg of ice into water at 0C.
Ans 2: Melting or fusion: when a substance is changed from solid to liquid state by adding heat, the process is called melting or fusion
Ans 3: Fusion or melting point : the temperature at which a solid starts melting is called its fusion or melting point. Different substances have different melting points.
Ans 4: Freezing point: the temperature at which a substance changes from liquid to solid state is called its freezing point. the freezing and melting point of a substance are same.
Ans 5: Experiment: take a beaker and place it over a stand. Put small pieces of ice in the beaker and suspended a thermometer in the beaker to measure the temperature. Place a burner under the beaker. The ice will start melting. The temperature of the mixture containing ice and water will not increase above 0C until all the ice melts. Note the time which the ice takes to melt completely into water at 0C.
Continue heating the water at -C in the beaker . Its temperature will begin to increase. Note the time which the water in the beaker takes to reach its boiling point at 100C from 0C.

Question # 4

Define and explain heat capacity

Ans 1: Heat capacity: heat capacity of a body is the quantity of thermal energy absorbed by it for one kelvin(1K) increase in its temperature.
Ans 2: Explanation; heat capacity of a body is equal to the product of its mass of the body and its specific heat capacity. For example, heat capacity of 5kg of water is (5kg*4200JKg^-1) 21000JK^-1. That is 5kg of water needs 21000J of heat for every 1K rise in its temperature. thus, larger is the quantity of substances, larger will be its heat capacity.
The presence of large water reservoirs such as lakes and seas keep the climates of nearby land moderate due to the large heat capacity of these reservoirs.

Question # 5

Explain the consequences and also application of thermal expansion.

Ans 1: Consequences of thermal expansions: the expansion of solids may damage the bridge, railway tracks and roads as they are constantly subjected to temperature changes. So provision is made during construction for expansion and contraction with temperature. For example, railway tracks bucked on a hot summer day due to expansion if gaps are not left between sections.
Bridge made of steel girders also expands during the day and contract during night. They will bend if their ends are fixed. to allow thermal expansions, one end is fixed while the other end of the girder rests on rollers in the gap left for expansion. Overhead transmission lines are also given a certain amount of sag so that they can contract in winter without snapping.
Ans 2: Application of thermal expansion: thermal expansion is used in our daily life. In thermometers, thermal expansion is used in temperature measurements. To open the cap of a bottle that is tight enough, immerse it in hot water for a minute or so. Metal cap expands and becomes loose. It would now be easy to turn it to open.
To join steel plates tightly together, red hot rivets are forced through holes in the plates. The end of hot rivet is then hammered. On cooling, the rivets contract and bring the plates tightly gripped. Iron rims are fixed on wooden wheels of carts. Iron rims are heated. Thermal expansion allows them to slip over wooden wheel. Water is poured on it to cool. The rim contracts and become tight over the wheel.

Question # 6

Briefly explain thermal expansion of liquids

Ans 1: Thermal expansion of liquid: there molecules of liquids are free to move in all directions within the liquid. On heating a liquid, the average amplitude of vibration of its molecules increases. The molecule's push each other and need more space to occupy. This account for the expansion of the liquid when heated. The thermal expansion in liquids is greater than solids due to the weak forces between their molecules. Therefore, the coefficient of volume expansion of liquids is greater than solids. Liquids have no definite shape of their own. A liquid always attains shape of container in which it is pored. Therefore, when a liquid is heated, both liquid and the container
Ans 2: Types:
- Apparent volume expansion
- Real volume expansion
Ans 3: Experiment: take a long-necked flask. Fill it with some colored liquid up to the mark A on its neck>Now start heating the flask from bottom. The liquid level first falls to b and then rises to C.
The heat first reaches the flask and its level falls to B. After sometime, the liquid begins to rise above B on getting hot. At certain temperatures it reaches at C. The rise in level A to C is due to the apparent expansion because of the expansion of the glass flask. Thus real expansion of the liquid is equal to the expansion because of the expansion of the glass flask. Thus real expansion of the liquid is equal to the volume difference between A and C in addition to the volume expansion of the flask. Hence
real expansion of the liquid= Apparent expansion of the liquid Expansion of the flask
BC+ AC+AB
The expansion of the volume of a liquid taking into consideration the expansion of the container also , is called the real volume expansion of the liquid. The real rate of volume expansion B, of a liquid is defined as the actual change in the unit volume of a liquid for 1K rise in its temperature. The real rate of volume expansion Br is always greater than the apparent rate of volume expansion Ba by an amount equal to the rate of volume expansion of the container Bg.
Thus,
Br=Ba+Bg where Br, Ba and Bg are represent Beta
It should be noted that different liquids have different coefficients of volume expansions.

Question # 7

Write a note on volume thermal expansion of solids

Ans 1: Volume thermal expansion; the volume of a solid also changes with the change in temperature and is called volume thermal expansion or cubical thermal expansion
Ans 2: Explanation: consider a solid of initial volume V_o at certain temperature T_o. On heating the solid to a temperature T, let its volume becomes V, then
change in the volume of solid=V-V_o
change in temperature= T-T_o

Question # 8

Define latent heat of vaporization. explain it

Ans 1: Latent heat of vaporization: the quantity of heat that changes unit mass of a liquid completely into gas at its boiling point without any change in its temperature is caked latent heat of vaporization.
It is denoted by H_v.
When water is heated, it boils at 10C under standard pressure. its temperature remains 100C until it is changed completely into steam. Its latent heat of vaporization is 2.26*10⁶JKg^-1That is 1kg of water requires 2.26*10⁶J heat to change it completely into gases at its boiling point.
Ans 2: Experiment: take a beaker and place it over a stand. put small pieces of ice in the beaker and suspended a thermometer in the beaker to measure the temperature. Place a burner under the beaker. The ice will start melting. The temperature of the mixture containing ice and water will not increase above 0C until all the ice melts. Note the time which the ice take to melt completely into water at )C. Continue heating the water at 0C in the beaker. Its temperature will begin to increase. Note the time which the water in the beaker takes to reach its boiling point at 100C from 0C.
Continue heating water till all the water changes into steam. Note the time which the water in the beaker takes to change completely into steam at its boiling point 100C.

Question # 9

Write a note on linear thermal expansion in solids

Ans 1: Thermal expansion; when heat is provided to any substances, the expansion of substances is known as thermal expansion.
Most of the substances solids, liquids and gases expand on heating and contract on cooling. Their thermal expansions and contractions are usually small and are not noticeable.
The kinetic energy of the molecule of an object depends on its temperature. The molecules of a solid vibrate with larger amplitude at high temperature than at low temperature.
Thus, on heating, the amplitude of vibration increase.
Thermal expansion results an increase in length, breadth and thickness of a substance.
Ans 2: Linear thermal expansion of solids: the expansion of solid along in one direction is called linear thermal expansion of solid. It has been observed that solids expand on heating and their expansions is nearly uniform over a wide range of temperature .
Unit; the unit of coefficient of thermal expansion is K^-1

Question # 10

Explain the change of state of matter

Ans 1: Change of state of matter: Matter can be changed from one state to another. For such a change to occur, thermal energy is added to or removed from a substance
Ans 2: Experiment: take a beaker and place it over a stand. put small piece of ice in the beaker and suspended a thermometer in the beaker to measure the temperature of ice.
Now place a burner under the beaker. The ice will start melting . The temperature of the mixture containing ice and water will not increase above 0C until all the ice melts and we get water at 0C. If this water 0c is further heated, its temperature will begin to increase above 0C.

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Matric Part 1/9th Class Physics Chapter 8 Long Question With Answer for Unit 8 Thermal Properties of Matter

9th Class English Medium Subjects

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Online Long Questions For Chapter 8 "9th Class Physics Chapter 8 Long Question Preparation "

Physics (New Book) - 9th Class Physics Chapter 8 Long Question Preparation

Explain the temperature , heat , thermal equilibrium and internal energy

What is bimetal strip ? explain and write its uses

Define latent heat of fusion and explain it

Define and explain heat capacity

Explain the consequences and also application of thermal expansion.

Briefly explain thermal expansion of liquids

Write a note on volume thermal expansion of solids

Define latent heat of vaporization. explain it

Write a note on linear thermal expansion in solids

Explain the change of state of matter

Prepare Complete Set Wise Questions For Chapter 8 "9th Class Physics Chapter 8 Long Question Preparation "

Set 1

Set 2

9th Class Physics Chapter 8 Long Question Preparation - Set 1

Explain the temperature , heat , thermal equilibrium and internal energy

What is bimetal strip ? explain and write its uses

Define latent heat of fusion and explain it

Define and explain heat capacity

Explain the consequences and also application of thermal expansion.

Briefly explain thermal expansion of liquids

Write a note on volume thermal expansion of solids

Define latent heat of vaporization. explain it

Write a note on linear thermal expansion in solids

Explain the change of state of matter

9th Class Physics Chapter 8 Long Question Preparation - Set 2

Briefly explain thermal expansion of liquids

Explain the consequences and also application of thermal expansion.

Q no: 7(A) What causes a glider to remain air.?

Q no 6B) How much heat is required to charge10 g of water °C into of vaporization of water is 2.26 x 106 J kg-¹

Explain the temperature , heat , thermal equilibrium and internal energy

Q no: 7 (B) Normal temperature of is 98.6 F. Convert it in the Celsius scale and .

Write a note on linear thermal expansion in solids

Define latent heat of vaporization. explain it

What is thermometer? explain it. write the thermometric properties of liquid

Q no: 6(A) Explain land and Sea breeze are example of convection.?

9th class Physics Chapter 8 Long Q's (English Medium)

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Q no 6B) How much heat is required to charge10 g of water °C into of vaporization of water is 2.26 x 10⁶ J kg-¹