If you you want to view notes of Physics 9th Click Here.
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Definitions
1. Internal Energy
Internal Energy of a body is the sum of all kinetic and potential energy of all molecules constituting the body.
2. Joules
It is the amount of heat required to rise the temperature of 1/4200 kg of pure water from 14.5 C to 15.5 C.
3. Calorie
It is the amount of heat required to rise the temperature of 1 g of pure water from 14.5C to 15.5C.
4. British Thermal Unit
It is the amount of heat that is required to rise the temperature of 1 pound of pure water from 63F to 64F.
Difference Between Heat and Temperature
Heat
* Heat is the energy in transit from one body to another due to temperature difference.
* It is the total kinetic energy of the body.
* Heat is measured using Joule meter.
* Its unit is Joule.
Temperature
* Temperature is the degree of hotness or coldness of a body.
* It is the average kinetic energy of the body.
* Temperature is measured using thermometer.
* Its units are F, C and K.
Thermal Expansion
Change in length, breadth and height of a body due to heating is known as Thermal Expansion. It occurs in all the three states, i.e. solids, liquids and gases.
Thermal Expansion of Solids
Solids expand on heating. Their ability to expand depends on their molecular structure. As the temperature is increased, the average kinetic energy of the molecules increases and they vibrate with larger amplitudes. This results in increase in the distance between them. Hence, they expand on heating. Thermal Expansion of solids can be classified into three types.
1. Linear Thermal Expansion
Change in length or any one dimension of a solid on heating is known as LInear Thermal Expansion.