Thermodynamics Block of Copper Problem

In summary, the equilibrium temperature of the two-block system is 317K. The change in the internal energy of the two-block system is -594K and the change in the entropy of the two-block system is +2K.
  • #1
flythisforme
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Hi, I need help with this problem for physics. I know it has something to do with Q=mcT. I can probably do parts b and c if I just get a start on part a. I'm just not sure how to approach it. Any help is appreciated. =)

A 50g block of copper having a temperature of 400K is placed in an insulating box with a 100g block of lead having a temperature of 200K. a) What is the equilibrium temperature of this two-block system? b) What is the change in the internal energy of the two-block system as it goes from the initial condition to the equilibrium condition? c) What is the change in the entropy of the two-block system?

Thanks in advance,
Cara
 
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  • #2
Actually part a) is the simplest.Compute the heat each body need to change (either accept or receive) in order to reach equilibrium.Then use the "insulating box" part...

Daniel.
 
  • #3
Well I just calculated that the initial heat of the copper is 7720J and the initial heat of the lead is 2560J, but how would I calculate how much heat they need to accept or receive in order to reach equilibrium?
 
  • #4
U have a copper block at 400K and this cools till he reaches equilibrium temp:x (unknown).

The heat lost is

[tex]Q_{lost}=m_{Co}c_{Co}\left(400-x\right) \ [J] [/tex]

The lead block heats from 200K till equilibrium temp."x".

The heat received

[tex] Q_{received}=m_{Pb}c_{Pb}\left(x-200\right) \ [J] [/tex]


What is the connection between the 2#-s (i used no sign convention:both #-s are positive (i hate sign conventions in thermo & geom.optics)) ??

Daniel.
 
  • #5
Sorry I stopped posting after. I had to run out really quick unexpectedly. I did what you said and I got 794K as an equilibrium temperature, but that doesn't make sense. Maybe I did it wrong? You probably aren't there anymore but if you aren't, if someone else wants to help me that would be awesome.
 
  • #6
actually I take that back, I got 317K now. So then would that be the answer for part a?

Also, when I do get the equilibrium temp. for part (a), for part (b) would I find the change in internal energy for each block and add the two values together? And as far as finding that, what would be the best equation to use?

would I use an internal energy equation for an isochoric system?
 
Last edited:
  • #7
I'm just trying to get this thread back up higher since I'm not getting any responses. I still need some help. I'd really appreciate it!
 

FAQ: Thermodynamics Block of Copper Problem

1. What is the thermodynamics block of copper problem?

The thermodynamics block of copper problem refers to a common problem in thermodynamics where a block of copper is heated to a certain temperature and then placed in a container of water at a lower temperature. The goal is to determine the final temperature of the water-copper system.

2. Why is the thermodynamics block of copper problem important?

This problem is important because it allows us to apply fundamental thermodynamic principles, such as conservation of energy and heat transfer, to a real-life scenario. It also helps us understand the behavior of materials when they undergo temperature changes.

3. How do you solve the thermodynamics block of copper problem?

To solve this problem, we can use the principles of heat transfer and conservation of energy. We can calculate the amount of heat transferred from the copper block to the water using the specific heat capacity of copper and the change in temperature. Then, we can use the conservation of energy equation to determine the final temperature of the water-copper system.

4. What factors can affect the solution to the thermodynamics block of copper problem?

The solution to this problem can be affected by various factors such as the initial temperature of the copper block and the water, the mass and specific heat capacity of the copper block, and the amount of water in the container. Additionally, the efficiency of the heat transfer process and any external factors, such as insulation, can also impact the solution.

5. How is the thermodynamics block of copper problem related to the second law of thermodynamics?

The second law of thermodynamics states that heat will naturally flow from a hotter object to a colder object until both reach the same temperature. In the thermodynamics block of copper problem, the heat transfer from the hot copper block to the cooler water follows this law, resulting in thermal equilibrium between the two objects.

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