Which unit measures energy in the SI system?

The unit that measures energy in the SI system is Joules. 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. This makes it a fundamental unit for measuring energy in various forms, including mechanical, electrical, and thermal energy.

In contrast, Pascals are units of pressure, Watts are units of power (the rate at which energy is consumed or produced), and Newtons are units of force. Each of these units has its own specific application and context, making Joules the correct choice when specifically looking for a measure of energy. Understanding the distinct roles of these units helps clarify their importance in various scientific and engineering calculations.