How Many Laws of Thermodynamics Are There?

  • Thread starter Thread starter LENIN
  • Start date Start date
AI Thread Summary
The discussion centers on the number of laws of thermodynamics, with participants noting that there are four recognized laws, including the 0th law, which addresses thermal equilibrium. The 1st law emphasizes the conservation of energy, stating that heat equals the change in internal energy plus work done on the system. The 2nd law highlights that entropy tends to increase over time, while the 3rd law states that absolute zero cannot be reached. Participants express confusion about the laws and seek clarification on the implications of absolute zero in relation to quantum mechanics. The conversation reflects a mix of formal definitions and informal interpretations of the laws.
LENIN
Messages
101
Reaction score
1
How many laws of thermodinamics are there?

This topic came up during one of our last hours of higschool physics. Some of us sead that there are 4 and some sead that there are only 2. In different books we also found different answeres. So now I really don't know which statement is corect. Any ideas?
 
Physics news on Phys.org
0th law - If a system, C is in thermal equilibrium with two other systems, A and B, then A and B must also be in thermal equilibrium.

1st law - Heat = Change in Internal Energy + Work done on the system. (Conservation of energy effectively).

2nd law - Entropy always increases with time.

3rd law - No object can ever reach a temperature of absolute zero.

A nice discussion of laws 1-3 can be found here.
http://www.physlink.com/Education/AskExperts/ae280.cfm

Claude.
 
1st Law: You can't win; you can only break even

2nd Law: You can only break even if you get to absolute zero.

3rd Law: You can't get to absolute zero.
 
rdt2 said:
1st Law: You can't win; you can only break even

2nd Law: You can only break even if you get to absolute zero.

3rd Law: You can't get to absolute zero.

you are forgetting a law here, see the above post

marlon
 
But i don't know why we can not reach the zero absolute temperature. Who can explain?
 
Essentially, because a particle at 0K violates the HUP. Google the 3rd law of thermodynamics and you should find some satisfying explanations.

Claude.
 

Thread 'The Effect of Linear and Rotational Motion on Measured Weight'

Consider an extremely long and perfectly calibrated scale. A car with a mass of 1000 kg is placed on it, and the scale registers this weight accurately. Now, suppose the car begins to move, reaching very high speeds. Neglecting air resistance and rolling friction, if the car attains, for example, a velocity of 500 km/h, will the scale still indicate a weight corresponding to 1000 kg, or will the measured value decrease as a result of the motion? In a second scenario, imagine a person with a...
View full post »

Thread 'Simple thought experiment with Stefan-Boltzmann law: energy'

Dear all, in an encounter of an infamous claim by Gerlich and Tscheuschner that the Greenhouse effect is inconsistent with the 2nd law of thermodynamics I came to a simple thought experiment which I wanted to share with you to check my understanding and brush up my knowledge. The thought experiment I tried to calculate through is as follows. I have a sphere (1) with radius ##r##, acting like a black body at a temperature of exactly ##T_1 = 500 K##. With Stefan-Boltzmann you can calculate...
View full post »
Thread 'Griffith, Electrodynamics, 4th Edition, Example 4.8. (First part)'

Thread 'Griffith, Electrodynamics, 4th Edition, Example 4.8. (First part)'

I am reading the Griffith, Electrodynamics book, 4th edition, Example 4.8 and stuck at some statements. It's little bit confused. > Example 4.8. Suppose the entire region below the plane ##z=0## in Fig. 4.28 is filled with uniform linear dielectric material of susceptibility ##\chi_e##. Calculate the force on a point charge ##q## situated a distance ##d## above the origin. Solution : The surface bound charge on the ##xy## plane is of opposite sign to ##q##, so the force will be...
View full post »

Similar threads

I How Does Temperature Affect Wire Tension at Constant Length?
Replies
4
Views
2K
B How is a Scientific law/theory's accuracy tested?
Replies
16
Views
2K
I How would the laws of thermodynamics change in a contracting universe?
Replies
5
Views
2K
B How are thermodynamic laws related to one another?
Replies
4
Views
2K
I Empirical temperature scales using different thermometers
Replies
7
Views
2K
Classical Looking for a thermodynamics book that 'ties it all together'
Replies
10
Views
4K
I Work in hydrostatic system in cylinder with piston: P_int or P_ext?
Replies
5
Views
2K
Could the Laws of Physics Be Proportional to Entropy?
Replies
5
Views
142
B Entropy change for reversible and irreversible processes
Replies
12
Views
2K
B Implicit error margins based on significant figures
Replies
18
Views
2K

Hot Threads

Recent Insights

Back
Top