# FBISE 9th Class Physics Chapter 8 Thermal Properties Short Questions Answers

FBISE 9th class Physics Chapter 8 Thermal Properties Short Questions with answers are combined for all 9th class(Matric/ssc) Level students. Here You can prepare all Physics Chapter 8 Thermal Properties short question in unique way and also attempt quiz related to this chapter. Just Click on Short Question and below Answer automatically shown. After each question you can give like/dislike to tell other students how its useful for each.

Class/Subject: 9th Class Physics

Chapter Name: Thermal Properties

Board: Federal  Board

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## FBISE 9th Class Physics Chapter 8 Thermal Properties Short Questions Answers

Define Haet?
Heat is the energy that is transferred from one body to the other in thermal contact with each other as a result of the temperature difference.

Define thermometry and temperature.
Thermometry: The art of measuring temperature is termed thermometry.
Temperature: The degree of coldness or hotness of the body is a measure of its temperature.

Define internal energy.
The sum of kinetic energy and potential energy associated with the atoms, molecules, and particles of a body is called internal energy.

Define Thermal Equilibrium.
According to the principle of thermometry, if two objects at different temperatures are joined together, after a certain time they attain the same temperature. This is known as the thermal equilibrium.

Define thermometer.
The instrument which is used to measure the temperature is called a thermometer.

Define specific heat?
Specific heat of a substance is the amount of heat required to raise the temperature of 1 kg mass of that substance through 1K.

Define heat capacity?
The heat capacity of a body is the quantity of thermal energy absorbed by it for one Kelvin (1K) increases in its temperature.

Define latent heat of fusion?
The heat energy required to change a unit mass of a substance from solid to liquid state at its melting point without change in the temperature is called its latent heat of fusion.

Define latent heat of vaporization?
The quantity of heat that changes the unit mass of a liquid completely into a gas at its boiling point without any change in its temperature is called its latent heat of vaporization.

Define evaporation?
Evaporation is the changing of a liquid into vapors (gaseous state) from the surface of the liquid without heating it.

What is linear Expansion?
If a thin rod is heated, there is a prominent increase in its length as compared to its cross-sectional area. The expansion along the length or in one dimension is called linear expansion.

What is volume expansion?
Heating a block causes an increase in length, breadth, and thickness, i.e., the volume of the block increases that is known as volume expansion.

What do you know about the bimetallic strip (thermostat)?
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 the strip.

Why does heat flow from a hot body to a cold body?
Heat flows from warm to cold body because the energy state is higher. Heat flow moves energy from a higher temperature to a lower temperature. The bigger the difference in temperature between the two objects, the faster heat flows between them. When the temperature is the same there is no change in energy due to heat flow. Heat flows from a hot body to a cold body until thermal equilibrium is reached.

How does heating affect the motion of molecules of a gas?
The larger the temperature of gas the faster the molecules will move (temperature is proportional to the average kinetic energy of the particles) and the large the force they will exert, and the higher the pressure (pressure is the force exerted by the particles divided by the area). T ∝ K.E ∝

Write down some consequences of thermal expansion.
The expansions of solids many damage bridges, railway tracks, and roads as they are constantly subjected to temperature changes.
i. Prevision is made during construction for expansion and contraction with temperature.
ii. Railway tracks buckled on a hot summer day due to expansion if gaps are not left between sections.

Write down some applications of thermal expansion.
Thermal expansion is used in our daily life. In thermometers, thermal expansion is used in temperature measurements.
i. To open the cap of a bottle that is tight enough, immerse it in hot water for a minute or so. The metal cap expands and becomes loose. It would now be easy to turn it to open.
ii. To join steel plates tightly together, red hot rivets are forced through holes in the plates. The end of the hot rivet is then hammered. On cooling, the rivets contract and bring the plates tightly griped.

Write down some examples of the expansion of solids.
i. Pipes passing through deserts and plains are curved to allow expansion and contraction due to change of season.
ii. While laying rail tracks gaps are left at joints to avoid damages caused by expansion or contraction.

Why the temperature of a substance does not change while it is changing its state from solid to liquid?
When a substance is changing from a solid to a liquid state, the temperature of the substance remains the same. It is because the heat supplied to the substance is used to overcome the attractive force among the atoms or molecules of the solid and not to increase the temperature.

What are the basic properties of thermometric liquid?
i. It should be visible
ii. It should have uniform thermal expansion
iii. It should have a low freezing point
iv. It should have a high boiling point
v. It should be a good conductor of heat
vi. It should have a small specific heat capacity

What is an Anomalous expansion of water?
Water on cooling below 4°C begins to expand until it reaches 0°C. On further cooling, its volume increases suddenly as it changes into ice at 0°C. When ice is cooled below 0°C, it contracts i.e. its volume decreases like solids. The unusual expansion of water is called the anomalous expansion of water.

How does heating affect the motion of molecules of a gas?
On heating, the gas, the motion of the molecules becomes faster. As a result average K.E and temperature of gas increases.

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