What does the first law state?

What does the first law state?

• A. Energy is never conserved in any system.
• B. Energy can be transferred and transformed, but it cannot be created or destroyed.
• C. Entropy increases in all energy transfers.
• D. Temperature remains constant in all processes.

Answer: (B)

Energy conservation is being tested here. The first law states that energy can be transferred and transformed, but it cannot be created or destroyed. In any process, the total amount of energy in a system plus its surroundings remains the same; energy can move between objects and change forms—chemical energy can become kinetic energy, light, or heat—but the overall total stays constant. This principle lets us account for energy in everything from a swinging pendulum to a light bulb and a running engine. The other statements aren’t correct because they mix in ideas from other concepts: energy is not never conserved—in a complete accounting of a system and its surroundings, the total energy is conserved; entropy changes relate to the second law, not the first law; and temperature does not stay constant in all processes, since energy transfer can raise or lower temperature unless very specific conditions hold.

Energy conservation is being tested here. The first law states that energy can be transferred and transformed, but it cannot be created or destroyed. In any process, the total amount of energy in a system plus its surroundings remains the same; energy can move between objects and change forms—chemical energy can become kinetic energy, light, or heat—but the overall total stays constant. This principle lets us account for energy in everything from a swinging pendulum to a light bulb and a running engine. The other statements aren’t correct because they mix in ideas from other concepts: energy is not never conserved—in a complete accounting of a system and its surroundings, the total energy is conserved; entropy changes relate to the second law, not the first law; and temperature does not stay constant in all processes, since energy transfer can raise or lower temperature unless very specific conditions hold.