According to the first law of thermodynamics, if heat added to a system exceeds the work done by the system, what happens to the internal energy?

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Multiple Choice

According to the first law of thermodynamics, if heat added to a system exceeds the work done by the system, what happens to the internal energy?

The amount of energy stored inside a system (its internal energy) changes according to the energy balance: ΔU = Q − W, where Q is heat added to the system and W is the work done by the system. If you add heat and the system does some work, part of that energy goes into doing work, but if the heat input is larger than the work done, the extra energy remains as internal energy. That makes ΔU positive, so the internal energy increases. For intuition, imagine a gas in a piston: heating raises molecular energy, and some energy may go into pushing the piston. If the heat input exceeds the energy used to do that work, the surplus energy shows up as higher internal energy (and usually higher temperature).

The amount of energy stored inside a system (its internal energy) changes according to the energy balance: ΔU = Q − W, where Q is heat added to the system and W is the work done by the system. If you add heat and the system does some work, part of that energy goes into doing work, but if the heat input is larger than the work done, the extra energy remains as internal energy. That makes ΔU positive, so the internal energy increases. For intuition, imagine a gas in a piston: heating raises molecular energy, and some energy may go into pushing the piston. If the heat input exceeds the energy used to do that work, the surplus energy shows up as higher internal energy (and usually higher temperature).

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