What best describes the energy in a closed system at the beginning of a day and the energy at the end of the same day? Choose three correct answers.

In a closed system, energy is conserved, so the total energy at the beginning equals the total energy at the end (A). Energy may change from one form to another, such as motion becoming thermal energy (C). Friction increases thermal energy as it converts some motion energy into heat (G); it does not destroy energy.

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