Which of the following best defines "internal energy"? The energy associated with moving against a force. B. The sum of all the thermal and kinetic energies of a system. C. The transfer of energy due to a difference in temperature. D. The thermal energy required to increase the temperature of a system 1 oC.

B-The sum of all the thermal and kinetic energies of a system

Explanation:

Internal energy within a thermodynamic system is made up of two parts, potential and kinetic energy. The energy of the internal system will depend on the work done on the system and/or heat given off or absorbed. If heat is released the internal energy will decrease, and if heat is absorbed, the internal energy will increase.