Chapter slides of chapter 11 physics part 1

1. Heat and thermodynamics
Muhammad Imtiaz
Cs, year 2
Namal College, Mianwali

2. Thermodynamics
 Heat:
 Heat is a form of energy.
 Thermodynamics:
 A branch of physics which deals with the energy and transformation of heat due to
matter into other forms of energy.

3. Kinetic theory of gases
 A finite volume of gas contain large numbers of atoms and molecules.
 The size of molecule is much smaller than the separation between molecules.
 Gas molecules are in random position and may change their direction after every
collision.
 Molecules do not exert force on each other except collision.
 The collision of molecules with themselves and with the wall of cylinder is perfectly
elastic.

4. Effect of pressure and temperature
 When gas molecules collide, they exert pressure on each other. In other words they
increase their Kinetic energy. So we can say that
 P K.E
 Also it increases temperature as well. so,
 T K.E

5. First law of thermodynamics
 Statement:
 In any thermodynamics process, when heat Q is added to the system this energy appears
as an increase in internal energy stored in the system plus work done by the system on
its surroundings.
 Q = ∆U + W
 Example:
 Bicycle pump
 Human metabolism

6. Isothermal and adiabatic process
 Isothermal process:
 A process in which temperature remains constant.
 Thus first law of thermodynamics:
 ∆U = 0 because temperature remains constant. i.e ∆T = 0
 Q = W
 Adiabatic process:
 The process in which no heat enters or leaves the system.
 i.e. Q = 0
 So, 1st law of thermodynamics will be
 Q = - ∆U

7. Molar specific heat of Gas
 Definition:
 The heat required to raise the temperature of one mole of gas, Called molar specific
heat of gas.
 Molar specific heat of gas at constant Volume:
 The heat required to raise the temperature of one mole of gas at constant volume
through 1K.
 Molar specific heat of gas at constant pressure:
 The heat required to raise the temperature of one mole of gas at constant pressure
through 1K.
 Relation:
 C 𝒑 − C 𝒗 = R

8. Second law of thermodynamics
 Statement:
It is impossible to devise a process or system which may convert heat entirely into work
without leaving any change in the working system.

9. Entropy
 Definition:
 The change in state of the system under natural process is termed as Entropy.
 Formula:
 ∆S = ∆Q / T

10. Thank you