Which law states that energy is neither created nor destroyed and that energy entering a process equals energy stored plus energy leaving?

Which law states that energy is neither created nor destroyed and that energy entering a process equals energy stored plus energy leaving?

• A. Zeroth Law of Thermodynamics
• B. First Law of Thermodynamics
• C. Second Law of Thermodynamics
• D. Third Law of Thermodynamics

Answer: (B)

Energy cannot be created or destroyed. When energy flows into a process, it must either be stored inside the system or leave as heat or work. This is the First Law of Thermodynamics, the energy conservation principle. It expresses the energy balance: energy entering equals energy leaving plus the change in stored energy. The stored portion accounts for changes in internal energy, kinetic energy, and potential energy of the system. In steady state, where there is no accumulation, energy in equals energy out. For example, heating a gas in a cylinder: the added energy increases the gas’s internal energy and may do work on the surroundings or be lost as heat, but the total energy accounted for still balances. The Zeroth, Second, and Third Laws describe temperature equilibrium, the direction of processes via entropy, and behavior near absolute zero, respectively.

Energy cannot be created or destroyed. When energy flows into a process, it must either be stored inside the system or leave as heat or work. This is the First Law of Thermodynamics, the energy conservation principle. It expresses the energy balance: energy entering equals energy leaving plus the change in stored energy. The stored portion accounts for changes in internal energy, kinetic energy, and potential energy of the system. In steady state, where there is no accumulation, energy in equals energy out. For example, heating a gas in a cylinder: the added energy increases the gas’s internal energy and may do work on the surroundings or be lost as heat, but the total energy accounted for still balances. The Zeroth, Second, and Third Laws describe temperature equilibrium, the direction of processes via entropy, and behavior near absolute zero, respectively.