THERMODYNAMICS

Thermodynamics is a branch of science which deals with the interconversion of Various Forms of energies. In simple, it is the motion or trasmission of heat.

OR

Thermodynamics is a branch of science which deals with exchange of heat energy between the bodies and conversion of heat energy  to mechanical energy and vice-versa.

The First law Of Thermodynamics 

This law is a very special case of law of conservation of energy that describes processes in which only the energy transfers are by heat and work. heat of the system  is given by increase in internal energy plus work Done.

Heat of System= Internal energy + Work Done

Q=ΔU + W

Real World Examples:

A bicycle pump provides a good example. We Usually use pressure pump to fill air in our bicycles in day-to-day life. we pump handle or piston rapidly, it becomes hot due to mechanical work done on the gas inside the tube, raising their by internal energy. Such types of examples can be physically examine by anyone, anywhere in the world.

Second Law Of Thermodynamics

It is a very contraversial law because many scientists like Clausis, Kelvin and Kelvin-planck's gave their statement on this law. This is one of the Beauty of our physics.

According to clausis statement-- "It is impossible for a self- acting machine to transfer Heat from colder body to a hotter body without the aid of an external agency".

Real world Examples

Some of the real world examples are steam engine, Heat engine and Our refrigerator or cooling agents in our office and home. Heat engine works along the reverse direction of Refridgerator.

Working of refridgerator

The working unit of fridge takes heat from sink or interior of fridge at lower temperature, has a net amount of work done 'W' by an external agent (usually compressor of the fridge) and gives out a larger amount of heat to a hot body at atmospheric temperature. Thus, it transfer heat from a cold body to a hot body at expense of mechanical energy supplied to it by an external agent. The cold body is thus cooled more and more. That is why Back side of fridge is always hot.

The performance of fridge is expressed by means of "coefficient of performance" β

Zeorth Law Of Thermodynamics-

If two systems are at the same time in thermal equilibrium with third system, they are in equilibrium with each other.

"Every body has a property called temperaturte. When two bodies are in thermal equilibrium, their temperatures are equal and vice-versa".

Real world Applications-

Suppose, I have two glasses of water, one glass will have hot water and the other will contain cold water. Now, If I leave them on the table for a few hours they will attain thermal equilibrium with the temperature of the room.

2. Hot Coffee become cold.

3. Cold drinks becomes hot after some time.

Third Law Of Thermodynamics 

"At absolute zero, the entropy of a perfectly crystalline substance taken as zero".

Application Of THird Law-

The Third law of thermodynamics has been useful in calculating the absolute entropies of solids and liquids and gases at different temperatures. This law is also useful to calculate entropy Changed of a chemical or physical process.

Real world Examples

SORRY. There is no real world applications to observe Third law of thermodynamics. 

Only First, second and zeroth law are obserable.

Real Life Examples based on Combination of laws

Melting Ice Cube

Every day, ice needs to be maintained at a temperature below the freezing point of water to remain solid. On hot summer days, however, people often take out a tray of ice to cool beverages. In the process, they witness the first and second laws of thermodynamics. For example, someone might put an ice cube into a glass of warm lemonade and then forget to drink the beverage. An hour or two later, they will notice that the ice has melted but the temperature of the lemonade has cooled. This is because the total amount of heat in the system has remained the same, but has just gravitated towards equilibrium, where both the former ice cube (now water) and the lemonade are the same temperature. This is, of course, not a completely closed system. The lemonade will eventually become warm again, as heat from the environment is transferred to the glass and its contents.

Sweating in a Crowded Room

The human body obeys the laws of thermodynamics. Consider the experience of being in a small crowded room with lots of other people. In all likelihood, you'll start to feel very warm and will start sweating. This is the process your body uses to cool itself off. Heat from your body is transferred to the sweat. As the sweat absorbs more and more heat, it evaporates from your body, becoming more disordered and transferring heat to the air, which heats up the air temperature of the room. Many sweating people in a crowded room, "closed system," will quickly heat things up. This is both the first and second laws of thermodynamics in action: No heat is lost; it is merely transferred, and approaches equilibrium with maximum entropy.

Taking a Bath

Consider a situation where a person takes a very long bath. Immediately during and after filling up the bathtub, the water is very hot -- as high as 120 degrees Fahrenheit. The person will then turn off the water and submerge his body into it. Initially, the water feels comfortably warm, because the water's temperature is higher than the person's body temperature. After some time, however, some heat from the water will have transferred to the individual, and the two temperatures will meet. After a bit more time has passed, because this is not a closed system, the bath water will cool as heat is lost to the atmosphere. The person will cool as well, but not as much, since his internal homeostatic mechanisms help keep his temperature adequately elevated.

Flipping a Light Switch

We rely on electricity to turn on our lights. Electricity is a form of energy; it is, however, a secondary source. A primary source of energy must be converted into electricity before we can flip on the lights. For example, water energy can be harnessed by building a dam to hold back the water of a large lake. If we slowly release water through a small opening in the dam, we can use the driving pressure of the water to turn a turbine. The work of the turbine can be used to generate electricity with the help of a generator. The electricity is sent to our homes via power lines. The electricity was not created out of nothing; it is the result of transforming water energy from the lake into another energy form.

Copyrighted ©️ To N-N Tutorials 

Source: Class 11 waves and thermodynamics 

Author: NISHANT RAJ 

STAY SAFE KEEP LEARNING 

Idea by : N. Rani

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