Ask a Teacher

Search



notes on vectors?

In one-dimensional motion, only two directions are possible. So the directional aspect of the quantities like position, displacement, velocity and acceleration can be taken care of by using + and - signs. But in case of motion in two-dimensions (plane) or three dimensions (space), an object can have a large number of directions. In order to deal with such situations effectively, we need to introduce the concept of new physical quantities, called vectors, in which we take care of both magnitude and direction.
The physical quantities which have both magnitude and direction and obey the laws of vector addition are called vector quantities or vectors. A vector quantity is specified by a number with a unit and its direction.
Representation of a vector: A vector quantity is represented by a straight line with an arrowhead over it. The length of the line gives the magnitude and the arrowhead gives the direction. Suppose a body has a velocity of 40 kmh-1 due east. I 1 cm is chosen to represent a velocity of 10 Kmh-1, a line OA, 4 cm in length and drawn towards east with arrowhead at A will completely represent the velocity of the body. The point A is called head or terminal point and point O is called tail or initial point of the vector  
In a simpler notation, a vector is represented by single letter of alphabet either in bold face or with an arrow over it. For example, a force vector can be represented as  or F.


comments powered by Disqus