Which of the following is NOT an SI base unit?

• A. meter (m)
• B. newton (N)
• C. kelvin (K)
• D. second (s)

Answer: (B)

Verified step by step guidance

1. Step 1: Understand what SI base units are. SI base units are the fundamental units defined by the International System of Units (SI) from which all other units are derived. Examples include meter (m) for length, kilogram (kg) for mass, second (s) for time, kelvin (K) for temperature, ampere (A) for electric current, mole (mol) for amount of substance, and candela (cd) for luminous intensity.
2. Step 2: Identify the units given in the problem: meter (m), newton (N), kelvin (K), and second (s).
3. Step 3: Recall that the newton (N) is a derived unit, not a base unit. It is defined as the unit of force and can be expressed in terms of base units as \(\mathrm{N} = \mathrm{kg} \cdot \mathrm{m} / \mathrm{s}^2\).
4. Step 4: Confirm that meter (m), kelvin (K), and second (s) are all SI base units representing length, temperature, and time respectively.
5. Step 5: Conclude that the newton (N) is NOT an SI base unit because it is derived from the base units kilogram, meter, and second.