Motion is the change of position of an object with respect to time. To study the motion of the object. one has to study the change in position (x,y,z coordinates) of the object with respect to the surroundings. It may be noted that the position of the object changes even due to the change in one. two or all the three coordinates of the position of the objects with respect to time. Thus motion can be classified into three types:
(i) Motion in one dimension: Motion of an object is said to be one dimensional, if only one of the three coordinates specifying the position of the object changes with respect to time.
Example : An ant moving in a straight line, running athlete. etc.
(ii) Motion in two dimensions: In this type, the motion is represented by any two of the three coordinates. Example: a body moving in a plane.
(iii) Motion in three dimensions: Motion of a body is said to be three dimensional, if all the three coordinates of the position of the body change with respect to time.
Examples: motion of a flying bird, motion of a kite in the sky. motion of a molecule, etc.