period = 1/frequency or T = 1
f
frequency = 1/period or f = 1
T
In everyday language, most people use the terms speed and velocity interchangeably. In physics, however, they do not have the same meaning:
Speed is the rate at which an object covers distance - i.e., how fast is it moving and is mathematically expressed as:
time
⌾ a fast-moving object has a high speed and covers a relatively large distance in a short amount of time
⌾ a slow-moving object has a low speed and covers a relatively small amount of distance in the same amount of time
⌾ an object with no movement at all has a zero speed
In contrast, velocity (v) is the rate at which an object changes its position and is mathematically expressed as:
Δtime
⌾ Imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. Because the person always returns to the original position, the motion would never result in a change in position. Since velocity is defined as the rate at which the position changes, this frenzy of motion nevertheless results in zero velocity.
Wave velocity is the distance traversed by a periodic, or cyclic, motion per unit time and despite the technical differences in definition, commonly refers to the speed of wave propagation through a medium. It is mathematically expressed as:
wavelength (λ) x frequency (f)