Mechanics — Introduction to Quantities and Vector Algebra + 7 more topics

When we talk about things in mechanics, we're dealing with physical quantities. These are properties of an object or system that can be measured. We categorize them into two main types:

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Kinematics is all about describing motion. The key quantities we track are:

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When we talk about mechanics, work, energy, and power are fundamental concepts that describe how forces interact with objects over time and distance. They're all related, but each describes a slightly different aspect of motion and its causes.

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When something moves, or even just sits still, there are forces at play. A force is a vector quantity, meaning it has both a magnitude (how strong it is, measured in Newtons, N) and a direction. Forces cause objects to accelerate (speed up, slow down, or change direction), or to deform (change shape).

You'll encounter a few common types of forces:

Hooke's Law is a fundamental principle in mechanics that explains the elastic behavior of springs and other elastic materials. It states that the force needed to extend or compress a spring by some distance is directly proportional to that distance.

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When an object moves in a circular path, even at a constant speed, its velocity is constantly changing because its direction is always changing. Since acceleration is the rate of change of velocity, this means the object is always accelerating. This acceleration is called centripetal acceleration, and it always points towards the center of the circle.