Motion and forces Study Guide

In physics, quantities can be classified based on whether they possess directionality. A vector quantity is a physical measurement that is characterised by both a magnitude (its size or numerical value) and a specific direction. Without specifying both the magnitude and the direction, a vector quantity is not fully described. For instance, 'velocity' is a vector because it defines both how fast an object is moving (magnitude) and in what direction. This contrasts with scalar quantities, such as 'speed', which only have magnitude and no associated direction.

Speed is a measure of how fast an object is moving, calculated as the distance travelled per unit of time. Different objects and phenomena have characteristic speeds that are useful to recall for comparison and problem-solving. For instance, the speed of sound is significantly faster than typical human movement, while wind speeds can vary greatly but are generally much lower than the speed of light. Knowing these typical values helps develop an intuitive understanding of scale in physics and everyday situations.