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Thermodynamics Conceptual Question

  1. Apr 16, 2016 #1
    Hi! I'm new to the forums, so I apologize in advance if I'm posting my question in the wrong section. I'm studying thermodynamics right now, and I came across this sentence from my book:
    1. The problem statement, all variables and given/known data
    "When energy is added to a system and there is no change in the kinetic or potential energy of the system, the temperature of the system usually rises."
    2. Relevant equations
    Volume is proportional to Temperature
    Internal Energy= Bond energy + Thermal energy
    3. The attempt at a solution
    I'm confused. Wouldn't adding energy to the system increase the system's internal energy (therefore inc. its kinetic/potential energy)? The only way I can see the above statement to be true is if there was an increase in volume of the system. And since volume is proportional to temperature, the temperature of the system would also rise. Are my assumptions correct or am I overthinking it? :oldconfused:
     
  2. jcsd
  3. Apr 16, 2016 #2
    In this context, when they are talking about kinetic or potential energy, they are referring to the macroscale. The potential energy they are referring to is gravitational potential energy, and the kinetic energy they are referring to is based on the mass average velocity over each small localized volume including a huge number of molecules.

    Your interpretation that the internal energy increases and the temperature increases is totally correct.
     
  4. Apr 16, 2016 #3
    Thanks Chestermiller!
     
    Last edited: Apr 16, 2016
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