Moderate

By rubbing the objects together, their internal energy:

Correct answer: A. Increases

  • A. Increases
  • B. Remains constant
  • C. Decreases
  • D. Becomes Zero

Explanation

When objects are rubbed together, mechanical work is done on them, which increases their temperature. According to the first law of thermodynamics, the increase in temperature results in an increase in internal energy as energy is transferred from mechanical work to thermal energy. Therefore, the internal energy of the objects increases. Other options are incorrect because they do not account for the energy transformation that occurs during the process of rubbing.

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About First Law of Thermodynamics

The first law relates heat supplied, work done and the change in internal energy through energy conservation. Problems use sign conventions and apply the law to isothermal, adiabatic, isobaric and isochoric processes. Internal energy is a state function, while heat and work depend on the path followed.

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