The document summarizes the first law of thermodynamics. It states that energy cannot be created or destroyed, only changed from one form to another. The total amount of energy in the universe remains constant. Energy exists in many forms, including mechanical, heat, light, chemical and electrical. Thermodynamics is the study of energy and how it is transferred or changed from one system to another or between systems and their surroundings.

1. The First Law of
Thermodynamics
PREPARED BY: MANAN BHATT(17MSE003)

2. The First Law of Thermodynamics
FIRST LAW OF THERMODYNAMICS
→ CONSERVATION OF ENERGY:
 Energy Can Be Changed From One Form To Another,
But It Cannot Be Created Or Destroyed.
 The Total Amount Of Energy And Matter In The
Universe Remains Constant, Merely Changing From One
Form To Another.
 Energy Exists In Many Forms, Such As Mechanical
Energy, Heat, Light, Chemical Energy, And Electrical
Energy.
 Energy Is The Ability To Bring About Change Or To Do
Work.
 Thermodynamics Is The Study Of Energy.

3. Surroundings
The Boundary Of The System Is Arbitrarily Chosen
 The System Can Exchange Mass And Energy Through The
Boundary With The Environment.
 An Example Of “Closed System” - No Mass Flow- Is The Gas
Confined In A Cylinder. The Boundary –In This Case Real Wall- Is
Made By The Cylinder And The Piston Walls.
System

4.  An Isothermal Process Is One Where The Temperature
Does Not Change.

5.  In Order For An Isothermal Process To Take Place, We
Assume The System Is In Contact With A Heat Reservoir.
 In General, We Assume That The System Remains In
Equilibrium Throughout All Processes.
 An Adiabatic Process Is One Where There Is No Heat Flow
Into Or Out Of The System.

6.  An Isobaric Process Occurs At Constant Pressure; An
Isovolumetric One At Constant Volume.
 If The Pressure Is Constant, The Work Done Is The
Pressure Multiplied By The Change In Volume:

7.  For Processes Where The Pressure Varies, The Work Done
Is The Area Under The P-V Curve.

8.  If We Apply The First Law Of
Thermodynamics To The Human Body:
We Know That The Body Can Do Work. If The Internal
Energy Is Not To Drop, There Must Be Energy Coming
In. It Isn’t In The Form Of Heat; The Body Loses Heat
Rather Than Absorbing It.
Rather, It Is The Chemical Potential Energy Stored In
Foods.

9.  The Metabolic Rate Is The Rate At Which Internal
Energy Is Transformed In The Body.
For 65kg person

10. THANK YOU