Table of Contents
Explain why heat is a type of energy.
We know that energy can be converted from one form to another. Heat can also be converted into other forms of energy and vice-versa. This means that heat is a type of energy. For example, when an electric bulb is lit, the electrical energy in the filament is converted into heat energy, and then heat energy is converted into light energy.
What is heat transfer? Explain.
We know that matter is made up of countless atoms and molecules. The vibration of these atoms and molecules causes heat to be transferred from one place to another in a substance. The transfer of heat from one object to another is called heat transfer. There are three ways in which heat can be transferred: conduction, convection, and radiation.
How is heat transferred in a solid? Explain.
Heat is transferred in a solid by the process of conduction. The molecules in a solid are closely packed. When heat is applied, the molecules of the solid absorb heat energy and vibrate in their place. The vibration of one molecule causes the vibration of the neighboring molecule, and thus heat is transferred from one molecule to another through vibration. In this way, heat is transferred from one end of a solid to the other end by the process of conduction.
How is heat transferred in liquid and gaseous substances? Explain.
Heat is transferred in liquid and gaseous substances by the process of convection. When heat is applied, the molecules of the hotter part of the liquid and gaseous substance absorb heat and become lighter, and rise up to the cooler part. And the denser cold molecules move down to the hotter part. These cold molecules again absorb heat, become hot, and similarly change their place and make room for other cold molecules. In this way, the molecules change their place and transfer heat with the help of their own motion.
What is absolute zero? Explain.
There is a minimum value of temperature that can be approached but never reached. This temperature is called absolute zero. The Kelvin scale is created by taking this absolute zero as zero degree. In the Celsius scale, this temperature is -273.15oC.
On what does the internal energy of an object depend? Explain.
When heat is applied to an object, the kinetic energy of the particles in the object increases, resulting in tan increase in internal energy. The temperature of the object also increases during this process. The internal energy of the particles in an object depends on the temperature of the object. The higher the temperature of an object, the more kinetic energy its particles have, and the greater its internal energy.
Explain the heat exchange between two objects at different temperatures in the light of internal energy.
When two objects at different temperatures are brought into contact, heat energy is transferred from the hotter object to the colder object. During this process, the kinetic energy and internal energy of the particles in the hotter object decrease, while the kinetic energy and internal energy of the particles in the colder object increase. This process continues until the temperatures of the objects become equal, or in other words, until the average kinetic energy or average internal energy of the particles becomes equal.
