Speed And Its Units

What is Speed?

Speed is defined as

The rate of change of position of an object in any direction.

It is measured as the ratio of distance to the time in which the distance was covered. Speed is a scalar quantity as it has only direction and no magnitude.

Speed Formula

The formula of speed is given in the table below:

\(s= \frac{d}{t}\)


  • s is the speed in m.s-1
  • d is the distance traveled in m
  • t is the time taken in s

Speed Unit

Following are the units of speed are:

CGS system  cm.s-1
SI system  ms-1

Dimensional Formula of Speed

The mathematical representation of speed is:
\(Speed = \frac{Distance}{Time}\) Dimensional formula of distance = M0L1T0
Dimensional formula of time = M0L0T1
Therefore, the dimensional formula of speed = M0L1T-1

Types of Speed

There are five types of speed and they are:

  • Uniform speed
  • Variable speed
  • Average speed
  • Instantaneous 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 intervals of times.

Average speed: Average speed is defined as the uniform speed which is given by the ratio of total distance traveled by an object to the total time taken by the object.

Instantaneous speed: When an object is moving with variable speed, then the speed of that object at any instant of time is known as instantaneous speed.

Measurement of Speed

For the measurement of speed in vehicles, speedometers are used while measuring the distance odometers are used. Speed can also be calculated with the help of a graph. The Distance-time graph helps in understanding the speed of an object.

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