When we see some activities like a running boy, moving bus, etc., only one question puts in our mind how these things are moving. This one word is motion in Physics. The concept of motion is described by using some terms like velocity, speed, distance, acceleration etc. motion is described as changed in the position of a moving object at an instant of time or period of time.

### Speed and its types

Speed is one of the basic parameters for motion. It is quite different with speed as it is not only covered in length or distance. It is a scalar quantity with only magnitude, not direction. Galileo first discovered it. He gave the formula and definition of speed that is distance divided by time. It can be calculated in terms of constant, angular, Instantaneous, and average speed.

The formula of speed is given as

**s = d/t**

- s is the speed in m.s
^{-1} - d is the distance travelled in m
- t is the time taken in s

## Types of Speed

- Uniform speed: A object is said to be in uniform speed when the object covers equal distance in equal time intervals.
- Variable speed: A object is said to be in variable speed when the object covers a different distance at equal time intervals.
- Average speed: Average speed is defined as the uniform speed, which is given by the ratio of total distance travelled by an object to the total time taken by the object.
- Instantaneous speed: Speed of the object at any instant of time is known as instantaneous speed