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a piston in a heat engine does 500 joules of work, and 1,400 joules of heat are added to the system. determine the change in internal energy and explain how this example demonstrates the conservation of energy.

The situation given above can be answered through the concept of the First Law of thermodynamics which states that the change in internal energy is equal to the difference between the work done and the heat added to the system. The work done by the object is negative and the heat added is positive.
             change in internal energy = -500J + 1400 J = 900 J