Physics is a broad and complex field. It covers everything from sound and light to nuclear science and geology. Because of this, it's been divided into different branches so that scientists can specialize in their knowledge of physics.

Mechanics is one major branch of physics, and this focuses on the behavior of objects and the forces that act upon them. Classical mechanics and quantum mechanics are two sub-fields of this branch.

Another is thermodynamics, which is just what it sounds like: the study of heat, temperature, and energy. Though this is but a branch of physics, it is a broad and complex field all in itself, studied by many different types of scientists and engineers.

Because physics includes the study of light and sound, you can bet there are branches dealing with each of these. Acoustics is study of sound and waves, and optics is the study of light and its properties. Both of these fields help describe how we interact with the world around us through two of our most important senses.