Editing Speed (section)

===Difference between speed and velocity===
Speed denotes only how fast an object is moving, whereas [[velocity]] describes both how fast and in which direction the object is moving.<ref>{{cite book| last=Wilson | first=Edwin Bidwell | title=Vector analysis: a text-book for the use of students of mathematics and physics, founded upon the lectures of J. Willard Gibbs | series=Yale bicentennial publications | year=1901 | pages=125 | publisher=C. Scribner's Sons | hdl=2027/mdp.39015000962285?urlappend=%3Bseq=149}} This is the likely origin of the speed/velocity terminology in vector physics.</ref> If a car is said to travel at 60&nbsp;km/h, its ''speed'' has been specified. However, if the car is said to move at 60&nbsp;km/h to the north, its ''velocity'' has now been specified.

The big difference can be discerned when considering movement around a [[circle]]. When something moves in a circular path and returns to its starting point, its average ''velocity'' is zero, but its average ''speed'' is found by dividing the [[circumference]] of the circle by the time taken to move around the circle. This is because the average ''velocity'' is calculated by considering only the [[Displacement (vector)|displacement]] between the starting and end points, whereas the average ''speed'' considers only the total [[distance]] travelled.