Which statement accurately reflects the first law of thermodynamics?

Which statement accurately reflects the first law of thermodynamics?

• A. Energy can be created from nothing.
• B. Energy can be stored but not changed.
• C. Energy cannot be transferred between systems.
• D. Energy can be transferred and transformed, but it cannot be created or destroyed.

Answer: (D)

The main idea here is that energy is conserved. The first law of thermodynamics says energy can be transferred and transformed from one form to another, but it cannot be created or destroyed. In any process, the total energy of a system plus its surroundings stays the same, even as energy shifts between forms (like chemical energy turning into heat or light) or moves across boundaries as heat or work. A simple way to picture it is to track all forms of energy and see that what gains energy must come from what loses energy, keeping the total constant. This explains why energy can be transferred between systems and transformed, yet cannot pop into existence or vanish. The other statements conflict with this principle: creating energy from nothing would violate conservation; energy stored but not changed ignores the many real transformations energy undergoes; and saying energy can’t be transferred between systems contradicts how heat and work move energy.

The main idea here is that energy is conserved. The first law of thermodynamics says energy can be transferred and transformed from one form to another, but it cannot be created or destroyed. In any process, the total energy of a system plus its surroundings stays the same, even as energy shifts between forms (like chemical energy turning into heat or light) or moves across boundaries as heat or work. A simple way to picture it is to track all forms of energy and see that what gains energy must come from what loses energy, keeping the total constant.

This explains why energy can be transferred between systems and transformed, yet cannot pop into existence or vanish. The other statements conflict with this principle: creating energy from nothing would violate conservation; energy stored but not changed ignores the many real transformations energy undergoes; and saying energy can’t be transferred between systems contradicts how heat and work move energy.