Equilibrium - Understanding CCW Direction

 

Understanding CCW Direction

Force vectors, like all vectors, possess a direction. The direction can be described as being east, west, north or south. However, if the vector does not point in one of the cardinal directions, then additional directional information must be provided. There are several ways to do this. One way is to say something like 30° West of North. In expressing the direction in this manner, one is saying that the vector is not exactly due north but rotated towards the west of north by an amount of 30°.

Another means of expressing the direction of a vector involves the use of the counter-clockwise from east convention - sometimes abbreviated as CCW (for counter-clockwise). The Equilibrium Concept Builder utilizes this convention in expressing the direction of the given vectors. This convention describes a vector's direction as an angle of rotation of the vector in the counter-clockwise direction, beginning at east. As an example, north would be 90° CCW because if a vector starts at due East and has its arrowhead rotated 90°, then it will be pointing north. Similarly, a 180° CCW rotation will direct the vector due West. A vector having a direction of 170° CCW will have been rotated almost as far as West, but falling 10° short of it.

The animation below shows a variety of vectors and their corresponding CCW direction.

 

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