The document discusses the first law of thermodynamics. It states that the first law expresses that heat is a form of energy and that in thermodynamic processes, the total energy of the system and its surroundings remains constant. This means that heat energy cannot be created or destroyed, but can be transferred or converted to other forms of energy. Some examples of applications of the first law include light bulbs converting electrical to light energy and plants converting solar energy to chemical energy. The first law has limitations that the second law addresses, such as not specifying the direction of heat flow or whether a process is feasible.

1. PRESENTERS :
Tanvir Ahsan : ( 191-29-1501 )
Khayrul Alam : ( 191-29-1512 )

2. Presenting…
First law of
Thermodynamics.

3. Thermodynamics is the branch of physics that deals with the relationships
between heat and other forms of energy.
In particular, it describes how thermal energy is converted to and from
other forms of energy and how it affects matter. The fundamental
principles of thermodynamics are expressed in four laws.
THERMODYNAMICS

4. This is expressed mathematically as:
ΔU = Q – W, where ΔU is the change in the
internal energy, Q is the heat added to the
system, and W is the work done by the
system.
The First Law of Thermodynamics states that heat is a form of energy, and
thermodynamic processes are therefore subject to the principle of
conservation of energy.
This means that heat energy cannot be created or destroyed. It can, however,
be transferred from one location to another and converted to and from other
forms of energy.

5. Applications in life science
The first law may seem kind of abstract, but if we start to look at examples, we’ll find that
transfers and transformations of energy take place around us all the time.
Law of Energy Conservation , It has two applications mainly –
1. To calculate Heat Transfer
2. To calculate Work Transfer
For example:
1. Light bulbs transform electrical energy into light energy .
2. One pool ball hits another, transferring kinetic energy and making the second ball move.
3. Plants convert the energy of sunlight into chemical energy.
4. You are transforming chemical energy from your last snack into kinetic energy as you walk,
breathe, and move your finger to scroll up and down this page.

6. 5. Transformation of heat energy into mechanical energy in steam engine .
6. Moreover , batteries , electric bulbs are also applications of first law of thermodynamics.
Every device or machinery , which involve Heat and Work transfer processes , energy
conservation is used to evaluate different properties or parameters and thermal
efficiencies .
Examples :
Turbines
Boilers
Refrigerator
Heater
Compressors
Rockets
Bomb Explosion

7. The limitations of first law :
According to the first Law of Thermodynamics It doesn’t tell us –
1. About the direction of the flow of heat : The first law dosen’t indicate whether heat can flow
from a cold end to a hot end or not.
2. About the feasibility of the reaction whether the process is feasible or not.
3. practically it is not possible to convert the heat energy into an equivalent amount of work.
To overcome the limitations :
The second law of thermodynamics helps us to predict whether the reaction is feasible or not
and also tell the direction of the flow of heat . It also tells that energy cannot be completely
converted into equivalent work.