Internal Energy and Temperature Changes When Mechanical Work is Done on a System

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SUMMARY

When mechanical work is done on a system, the internal energy of the system increases, as dictated by the First Law of Thermodynamics, represented by the equation ΔU=Q-W. In scenarios where no heat transfer occurs (Q=0), the work done on the system directly contributes to an increase in internal energy (ΔU = -W). Consequently, this increase in internal energy results in a rise in the system's temperature. Therefore, performing work on a system unequivocally raises both its internal energy and temperature.

PREREQUISITES
  • Understanding of the First Law of Thermodynamics
  • Familiarity with the concepts of internal energy and temperature
  • Knowledge of mechanical work and its effects on thermodynamic systems
  • Basic grasp of heat transfer principles
NEXT STEPS
  • Study the implications of the First Law of Thermodynamics in various thermodynamic processes
  • Explore the relationship between internal energy and temperature in ideal gases
  • Investigate the effects of heat transfer on internal energy changes
  • Learn about different types of mechanical work and their impact on thermodynamic systems
USEFUL FOR

Students of thermodynamics, physics educators, and professionals in engineering fields who require a solid understanding of energy changes in mechanical systems.

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Homework Statement


What happens to the internal energy of a system and its temperature when mechanical work is done on it?

Homework Equations


ΔU=Q-W

The Attempt at a Solution


First Law of Thermodynamics say:the change in internal energy of the system is equal to the heat added to the system minus the work done by the system ΔU=Q-W
but what happen to the internal energy and temperature when mechanical work is done ON the system?
 
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As the equation for the 1st law of thermodynamics shows, what happens when mechanical work is done on a system depends also whether heat enters or leaves the system.
 
Last edited:
the part which is confusing me is the 1st law of thermodynamics say,the work is done by the system ,but the question clearly say the work is done on the system.
will it not have effect on the temperature within system?
 
Assume that there is no heat transfer out of, or into, the system.

Then when work is done ON the system, energy must be applied TO the system and hence its internal energy increases.

But when work is done BY the system, energy must be supplied BY the system and hence its internal energy decreases.
 
in that case what would happen to the temperature within system?
 
If the internal energy of the system increases the temperature will increase.
 

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