What is the standard unit for measuring energy?

The standard unit for measuring energy is the joule. The joule is a derived unit in the International System of Units (SI), where it represents the amount of energy transferred when an object is moved one meter against a force of one newton. It is a versatile unit applicable in various fields such as physics, chemistry, and engineering, allowing for consistent measurements of energy, work, and heat.

In contrast, other units listed serve different purposes. A calorie is primarily used to quantify energy in terms of heat, especially in nutrition and food science, while a watt is a measure of power, defined as one joule per second, and is used to express the rate of energy transfer. A volt measures electric potential difference, not energy itself. These distinctions underscore why the joule is recognized as the standard unit for energy measurement in scientific contexts.