Calorie (cal)
The calorie (cal) originated in the 19th century as a unit for quantifying heat energy. It was initially defined as the energy required to increase the temperature of one gram of water by one degree Celsius under standard atmospheric pressure. The calorie gained popularity in fields such as chemistry, physics, and nutrition. Despite not being an official SI unit, it remains prevalent on nutritional labels and in dietary contexts, particularly in the United States and Europe. Before the widespread adoption of the joule, the calorie played a significant role in standardizing energy measurements related to food and biological systems.
Joule (J)
The joule (J), recognized as the SI unit of energy, is named in honor of physicist James Prescott Joule. It represents the amount of work performed when a force of one newton moves an object over a distance of one meter. The joule is widely used in physics, thermodynamics, and engineering, providing a standardized way to quantify energy across mechanical, electrical, and thermal processes. Its implementation has enabled researchers and professionals to measure and compare energy values with accuracy and consistency around the globe.