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Change has a cost, and it is paid in energy.

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Energy fuels change in our universe. Physical systems exchange energy during interactions, much like humans exchange money.

We’ll start by deriving more traditional results - like the work-energy theorem and conservation of energy - before diving into applications of these laws of energy to the real world, from biology to inflating balloons:

All physical systems undergo change, from radioactive decay of atomic nuclei to galactic mergers. In these quizzes, we will lay the foundation for the principle of conservation of energy, which asserts that energy in the universe is eternal.

Chemical energy is stored in molecular bonds. Nuclear energy is stored in the configurations of particles in atomic nuclei. Electromagnetic energy is stored in electric fields. Even mass is a consequence of energy in matter fields. When accounting for all forms of energy, no experiment has been known to violate the principle of energy conservation. Truly, the concept of energy is central to physics.

Humans and other animals are agents of change in their environments; this means they do work. Like all other physical processes, the work we do is governed by the principle of energy conservation.

Energy enters our bodies in food as chemical energy, potential energy stored in molecular bonds. During metabolic chemical reactions, this energy is transferred to other molecules so that it is available for use in cellular processes, like muscle contraction.

We’ll relate the work done by muscles to an energy-releasing chemical reaction called ATP hydrolysis. Muscles, like engines, convert chemical energy to mechanical work via a process known as ATP hydrolysis, which provides a context for exploring two important energy concepts: efficiency and power.

Master the problem solving skills of Classical Mechanics.

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