Which of the following best describes a derived SI unit?

• A. A unit that is only used in non-SI measurement systems.
• B. A unit that is defined as a fundamental physical quantity in the SI system.
• C. A unit that is formed by combining two or more base SI units through multiplication or division.
• D. A unit that is used to measure temperature in the SI system.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the difference between base SI units and derived SI units. Base SI units are fundamental units defined for basic physical quantities such as length, mass, time, electric current, temperature, amount of substance, and luminous intensity.
2. Step 2: Recognize that derived SI units are formed by combining these base units through multiplication or division to express other physical quantities. For example, speed is distance divided by time, so its unit (meters per second) is derived from base units.
3. Step 3: Identify that a derived SI unit is not a unit exclusive to non-SI systems, nor is it a fundamental unit itself. It is also not specifically related to temperature measurement alone.
4. Step 4: Recall examples of derived SI units such as newton (N) for force, which is kg·m/s², or joule (J) for energy, which is N·m or kg·m²/s², illustrating how they combine base units.
5. Step 5: Conclude that the best description of a derived SI unit is a unit formed by combining two or more base SI units through multiplication or division.