Which of the following units is commonly used to measure energy in the International System of Units (SI)?

• A. joule
• B. kelvin
• C. newton
• D. watt

Answer: (A)

Verified step by step guidance

1. Understand that the International System of Units (SI) defines standard units for various physical quantities, including energy, temperature, force, and power.
2. Recall that energy is the capacity to do work or produce heat, and its SI unit must reflect this concept.
3. Identify the SI unit for energy, which is the joule (J). The joule is defined as the amount of energy transferred when a force of one newton moves an object one meter in the direction of the force.
4. Recognize that kelvin (K) is the SI unit for temperature, newton (N) is the SI unit for force, and watt (W) is the SI unit for power (rate of energy transfer), so these are not units of energy.
5. Conclude that among the given options, the joule is the correct and commonly used SI unit to measure energy.