How to Determine if Temperature Increase is Due to Work or Heat?

In summary, the conversation discusses how to determine whether an increase in temperature is due to work done or heat released. The conclusion is that in cases such as shaking a thermally insulated container or moving a block connected to a paddle immersed in water, the increase in temperature is due to work done rather than the addition of heat. This was first demonstrated by Joule in his experiment with the paddle.
  • #1
pardesi
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suppose a certain process is carried out on a system which say heats up the system the how do we decide that that's due to work done or heat released.
for example suppose i put water in an thermally insulated container and shake it and it's temp. increases then is it due to heat or work done
 
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  • #2
Once the energy is in the form of heat there is no difference in how the heat was initially generated.
 
  • #3
but my book says it's work done and not heat generated
 
  • #4
Heat flow requires a temperature difference. The issue is not "is thermal energy increased?"--of course it is. You can increase internal energy by doing work or by adding "heat". When you shake the water bottle, the increase in temperature is due to the work you've done.
 
  • #5
yes this is what i thought.Also what about this case
there is a paddle immersed in water fixed within which is connected to a movable block through a fixed pulley When the block moves the temp of the system rises is it work done or heat released .I think work done because the same reason as above .
Would like to know ur answers
 
  • #6
pardesi said:
Also what about this case
there is a paddle immersed in water fixed within which is connected to a movable block through a fixed pulley When the block moves the temp of the system rises is it work done or heat released .I think work done because the same reason as above .
Would like to know ur answers
Sure, that's a similar situation: the temperature increase is due to work done, not "heat" added. In fact, that paddle experiment was used by Joule to first show that mechanical work can be converted to "heat".
 

1. What is the difference between work done and heat released?

Work done is the transfer of energy from one system to another by a force acting over a distance. Heat released, on the other hand, is the transfer of thermal energy from a hotter object to a colder object.

2. How is work done related to the first law of thermodynamics?

The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or converted from one form to another. Work done is a form of energy transfer, and therefore, it is related to the first law of thermodynamics.

3. Can work done be negative?

Yes, work done can be negative. This occurs when the force applied is in the opposite direction of the displacement, resulting in the system losing energy instead of gaining it.

4. What factors affect the amount of work done or heat released in a system?

The amount of work done or heat released in a system depends on the amount of force applied, the distance over which the force is applied, and the properties of the system, such as its temperature and heat capacity.

5. How is work done or heat released measured?

Work done is typically measured in joules (J) or newton-meters (N*m), while heat released is measured in joules or calories (cal). The specific measurement method may vary depending on the system and the type of energy transfer.

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