What was the change in internal energy (chemical energy plus thermal energy) of the person pulling the block?

The internal energy is the sum of the heat absorbed or emitted and the work done.

The question is incomplete but I will try  to help you as much a possible. The term internal energy refers to all the energy that is contained in the system.

From the first law of thermodynamics, the internal energy is the sum of the heat absorbed or emitted and the work done. Hence we can write;

U = q + w.

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scientific laws are the result of testing theories and proving them to be facts.

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