Can anyone explain the three laws of Thermodynamics in simpler words and the definition of Entropy?

[hafeezrocks]

Nearly every definition of the Law is different on differentiate sources, anything simpler and what exactly is Entropy? Entropy of a System and Universe?

 

[indipper]

Entropy in urdu means 'ghatao'.

Entropy of a system means system is supposed to loose energy with increment in its size/use/resistance etc.

 

[Syed1]

Entropy cannot be understood lmao

 

[Syed1]

1st law:


Energy cannot be created or destroyed... it can only be changed from one form to another.


For example when a car is driving down the road it has kinetic energy.... suppose the car now applies hard brakes. The kinetic energy is converted into heat energy within the brakes for the most part

 

[Donal Cozzie]

 

[Rafa]

1st law:


Energy cannot be created or destroyed... it can only be changed from one form to another.


For example when a car is driving down the road it has kinetic energy.... suppose the car now applies hard brakes. The kinetic energy is converted into heat energy within the brakes for the most part

That's Kool but what about ,

Change in Internal Energy = Q ( Heat Transfer from Higher Temperature to Lower Temperature) - W ( Work) .... That's same right?

Why can't entropy be understood considering every law has mention of it?

 

[hafeezrocks]

Entropy cannot be understood lmao

Then how to know what entropy is?

 

[hafeezrocks]

1st law:


Energy cannot be created or destroyed... it can only be changed from one form to another.


For example when a car is driving down the road it has kinetic energy.... suppose the car now applies hard brakes. The kinetic energy is converted into heat energy within the brakes for the most part

2nd and 3rd Law? I need an explanation in terms of Thermodynamic terms like open and closed systems if possible and not Cars / Kinetic Energy.

 

[Syed1]

2nd and 3rd Law? I need an explanation in terms of Thermodynamic terms like open and closed systems if possible and not Cars / Kinetic Energy.

Ok you made me dig through my university notes. See if the attached helps you... I have similar for 2nd and 3rd laws as well.

 

[hafeezrocks]

Ok you made me dig through my university notes. See if the attached helps you... I have similar for 2nd and 3rd laws as well.

Can't see any images.

 

[Syed1]

Then how to know what entropy is?

See attached for entropy and exergy... The notes are my prof's notes for my thermo 2 class when he was doing a review for thermo 1. I'm sure the thermo 1 notes will be alot more in depth but my university has blocked access to courses taken before 2010.

 

[Syed1]

Can't see any images.

Click on the link... it will download.

 

[hafeezrocks]

OK downloaded, will read and get back. Thanks.

 

[Syed1]

OK downloaded, will read and get back. Thanks.

In the first pdf... scroll to page 6. It has what you are looking for.

 

[Hadi Rizvi]

Nearly every definition of the Law is different on differentiate sources, anything simpler and what exactly is Entropy? Entropy of a System and Universe?

Entropy can be interpreted in many ways but you could define it as a measure of disorder/chaos

Entropy is always discussed in terms of change. So you can't find the entropy of water but you can find the entropy change of vaporization of water.

Also entropy always increases.

So basically entropy change (increase in entropy) is always higher during boiling of water as compared to melting of ice.

 

[Rayyman]

Just took Gen Chem 2. Got a C+ I think.

I believe Entropy is the measurement of how spread out energy is.

TBH I usually try to understand concepts but this one in particular was hard.

So just memorize the equations I guess. Like S Universe and Gibbs Free Energy, etc.

Try to understand Spontaneity too.

 

[Nostalgic]

Wasn't entropy something to do with the Heat Death of the Universe?

I remember it from FSc Physics lessons. We were taught by a professor who used to take Thursdays off because he owned a bus plying the Rawalpindi-Peshawar route, and Thursdays were his driver's day off, so the professor himself drove the bus that day.

His name was Aftab Gul. We used to call him Sunflower. Get it?

 

[Sean143]

There are actually four laws of thermodynamics

Zeroth law:If two bodies are in thermal equilibrium with a third body then both these bodies are in equilibrium with each other as well.

First Law:The total energy in a system conserved if it disappears in one form it appears in another form(for example if you throw a ball from a height "h".Initially the ball possesses Potential Energy at that height but if dropped the P.E converts to Kinetic energy of the ball.

Second law:The change in entropy(disorder) in a system can never be negative.Either it is positive or it is zero in Ideal cases.
"For example the efficiency of steam engines is always less than hundred percent.The reason it that all the heat coming from heat source can't be converted to useful work and some heat has be to rejected cold reservoir"

Will explain concept of entropy in more detail later

 

[MRSN]

very good example of entropy of universe..
<iframe width="560" height="315" src="https://www.youtube.com/embed/uQSoaiubuA0" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

 

[R3verse Swing]

In a word, Entropy is a fancy way of saying, death. Everything winds down to Zero.