Category: Thermodynamics

According to the law of conservation of energy, the total energy of an isolated system remains constant over time. Understanding this principle is key to identifying which of the following factors do not contribute to total energy. While many factors can affect specific energy forms, only factors that are not part of the fundamental energy forms of a closed system, such as a system's color or density, are irrelevant to its total energy.

The science of calorimetry began with Joseph Black in the 18th century, who first distinguished between heat and temperature. So, what does calorimetry measure? It quantifies the amount of heat energy transferred during a physical or chemical process.

The enthalpy of hydration, also known as hydration energy, is always a negative value, meaning the process is exothermic. Understanding the **energy change of hydration** is fundamental to explaining why some salts release heat when they dissolve in water, while others absorb it.

Over 70% of American adults are overweight or have obesity, making the concept of energy balance critical for understanding weight management. The equation for energy balance explains the relationship between energy consumption and expenditure, determining changes in stored energy.

In a closed system, the total amount of energy remains constant according to the law of conservation of energy. Understanding what does the total energy include is fundamental to physics, as it comprises the sum of all forms of energy present within that system.

According to the first law of thermodynamics, the total energy of an isolated system remains constant; energy is not created or destroyed, but merely converted from one form to another. This means a system's total energy is a sum of its many constituent parts, but what is total energy made up of specifically?

According to Einstein's theory of special relativity, a body at rest possesses a tremendous amount of energy, even without any motion. This intrinsic energy, known as rest energy, is directly related to its mass through the iconic equation $E=mc^2$. Understanding what is the energy of a body at rest requires looking beyond simple kinetic energy to explore the fundamental nature of mass and energy.

The modern concept of a calorie has its roots in 18th-century chemistry and physics, long before it became a household term for dieting. The story of how were calories discovered involves key scientific developments in the measurement of heat, the study of combustion, and the understanding of energy conversion in both chemical reactions and biological organisms.

According to the second law of thermodynamics, not all energy in a system is available for useful work. The concept that quantifies this useful work potential is defined by the energy availability equation, a fundamental principle known as exergy in engineering and physics.

While the idea of a healthy body being a product of a simple, balanced input is appealing, applying the thermodynamic concept of a balanced diet state function is a scientific fallacy. Unlike ideal physical systems, biological outcomes are deeply dependent on the specific biochemical and physiological pathways taken to achieve nutritional balance.