Physics 141 Mechanics Lecture 3 Vectors
Motion in 2-dimensions or 3-dimensions has to be described by vectors.
In mechanics we need to distinguish two types of physical quantities: scalars or vectors.
A scalar has only magnitude, large or small, positive or negative, such as time, mass, temperature, etc. A single value in the right unit, together with a sign, completely specify a scalar.
A vector has not only the magnitude but also direction, such as displacement, velocity, acceleration, force, etc. A displacement cannot be specified by giving only the magnitude. The direction of the displacement must also be given.