As you see in the diagram mechanics is the first and most fundamental branch of physics, supporting Thermodynamics and Electricity, and including Statics, Dynamics(=Kinematics+kinetics); all which are all highly applicable in engineering. but the most important part of them is statics (study of body at rest) which is not only a base for all others, but also have the highest engineering application. physics also involve optics, waves, quantum, and relativity theory, which have no fundamental engineering application yet.

### Distinction between Physics and Engineering physics[edit]

Difference of pure and applied science### Prerequisites[edit]

This book assumes familiarity with high school physics and calculus, although the mathematics used is fairly elementary.

### Statics[edit]

We describe the motion of bodies using Newton's second law of motion

Statics deals with the situation where the acceleration is zero - which happens when a body is at rest, or moving with constant velocity. That means that the total force on a body at rest or with constant velocity must be zero. In other words, the sum of the forces on the body must equal zero.

Engineers typically draw what is called a "free body diagram" to show all forces on a body at rest. These forces are then broken down into vectors consistent with a useful coordinate system and summed in sets (components parallel to each basis vector) which are then set to zero to meet the static constraint of no acceleration being present.

This typically results in sets of equations which can be solved using simple linear algebra techniques or even simple algebra and substitution.