Conservation of Energy in Closed Systems

Steps:

• Recall the principle: Energy cannot be created or destroyed, only transformed.
• Define a closed system: No energy enters or leaves; total energy remains constant.
• Evaluate options: Check if each aligns with this principle.
• Select the match: Identify the statement that directly states the total energy constancy.

Why D is correct:

• The first law of thermodynamics states that the total energy in a closed system is constant, as energy is conserved regardless of conversions.

Why the others are wrong:

• A: Energy conversion does not conserve sources; it transforms energy forms while total energy stays the same.
• B: Conservation holds for all closed systems, not just 100% efficient ones; efficiency affects useful output, not total energy.
• C: The principle addresses energy constancy in systems, not limited supply or ethical conservation.

Final answer: D