**Speed in Physics Formula:**

The time rate of change of position of the object in any direction is called speed of the object.

Speed Formula in Physics

\(Speed (v)=\frac{\text { Distance travelled }(s)}{\text { Time taken }(t)}\)

- Its SI unit is m/s.
- It is a scalar quantity.
- Its dimensional formula is [M°LT
^{-1}].

## What is Speed in Physics? | Definition, Type, Formulas, Units – Motion in a Straight Line

We are giving a detailed and clear sheet on all Physics Notes that are very useful to understand the Basic Physics Concepts.

**Types of Speed in Physics**

**Uniform Speed Definition:**

If an object covers equal distances in equal intervals of time, then its speed is called uniform speed.

**Non-uniform Definition or Variable Speed:**

If an object covers unequal distances in equal intervals of time and vice-versa then its speed is called non-uniform or variable speed.

**Average Speed Definition:**

The ratio of the total distance travelled by the object to the total time taken is called average speed of the object.

\(Average speed =\frac{\text { Total distance travelled }}{\text { Total time taken }}\)

If a particle travels distances s_{1}, s_{2}, s_{3},… with speeds v_{1} v_{2}, v_{3},……., then

\(\text { Average speed }=\frac{s_{1}+s_{2}+s_{3}+\ldots}{\left(\frac{s_{1}}{v_{1}}+\frac{s_{2}}{v_{2}}+\frac{s_{3}}{v_{3}}+\ldots\right)}\)

If particle travels equal distances (s_{1} = s_{2} = s) with velocities v_{1} and v_{2}, then

\(\text { Average speed }=\frac{2 v_{1} v_{2}}{\left(v_{1}+v_{2}\right)}\)

If a particle travels with speeds v_{1}, v_{2}, v_{3},… during time intervals t_{1}, t_{2}, t_{3},…… then

\(\text { Average speed }=\frac{v_{1} t_{1}+v_{2} t_{2}+v_{3} t_{3}+\ldots}{t_{1}+t_{2}+t_{3}+\ldots}\)

If particle travels with speeds v_{1} and v_{2} for equal time intervals, i.e. t_{1} = t_{2} = t, then

\(Average speed =\frac{v_{1}+v_{2}}{2}\)

When a body travels equal distance with speeds v_{1} and v_{2}, the average speed (v) is the harmonic mean of two speeds, i.e.

\(\frac{2}{v}=\frac{1}{v_{1}}+\frac{1}{v_{2}}\)

**Instantaneous Speed Definition:**

When an object is travelling with variable speed, then its speed at a given instant of time is called its instantaneous speed.

\(\text { Instantaneous speed }=\lim _{\Delta t \rightarrow 0} \frac{\Delta s}{\Delta t}=\frac{d s}{d t}\)

**Motion in a Straight Line Topics:**