Motion

Motion:- We called an object to be in motion when its position changes with time.

Example:- Moving vehicles, flying Birds,  Riding Bicycles Etc.

Rest:-  Any motionless object is said to be at  rest.
                          -:Types of Motion:-

1) Motion in a straight line is called rectilinear motion.
Example:- Book on the table.

Example:- Moving car in a straight path.

2) In circular motion an object moves such that its distance from a fixed point remains the same.

Example:- The motion of a point marked on the blade of an electric fan or the hands of a clock are examples of circular motion

3) Motion that repeats itself after some period of time is called periodic motion.

Example:- A branch of a tree moving to and fro, motion of a child on a swing

Speed:-

We call the distance covered by an object in a unit time as the  speed  of the object.

So, for us the  speed is the total distance covered divided by the total time taken. 

Thus,

             Speed  =  Total distance covered  
                                   Total time taken

                             (Unit of speed is m/s )

In everyday life we seldom find objects moving with a constant speed over long distances or for long durations of time. If the speed of an object moving along a straight line keeps changing, its motion is said to be  non-uniform. On the other hand, an object moving along a straight line with a constant speed is said to be in  uniform motion. In this case, the average speed is the same as the actual speed.