Types of motion

In our daily life we see many objects moving. Some objects move in a straight line. For example, a ball rolling on a horizontal surface, a stone falling from a building and a runner on a 100m race track. In all these examples, objects change their positions with time along a straight line. This type of motion is called rectilinear motion.
Observe the motion of a second’s hand of a clock, or motion of a child sitting on a marry-go round, or the motion of the blades of an electric fan. In such a motion, an object follows a circular path during motion. This type of motion is called circular motion. If you take a stone, tie a thread to it and whirl it with your hand, you will find that the stone moves on a circular path. In all such cases, though an object changes its position with time, it remains at a fixed distance from a point.
Some objects move to and fro, such as a swing, a pendulum, the branches of a tree in the wind and the needle of a sewing machine. Such type of motion is called oscillatory motion. In such a motion, an object oscillates about a point, often called equilibrium position.