What is Motion ?

An object is said to be in motion if it changes its position with respect to its surroundings in a given time.


Uniform Motion


An object is said to be in uniform motion if it covers equal distances in equal intervals of time.


Non-Uniform Motion


A body is said to be in non-uniform motion if it covers unequal distances in equal intervals of time.

Speed


Speed is the distance covered per unit time of an object.
\[speed=\frac{distance}{time}\]

Velocity

Velocity is the displacement per unit time of an object.

\[\tiny \bf Average \ Velocity = \frac{initial \ velocity + final \ velocity}{2}\]
OR
\[\large v_{av}=\frac{{u} \ + \ v}{2}\]

Acceleration


The change in velocity per unit time of an object is called acceleration.

\[Acceleration=\frac{change \ in \ velocity}{time \ taken}\]
\[\therefore \ Acceleration=\frac{v-u}{t}\]



Motion - Equations and Formulas


Equations of motion Formula
First equation of motion v=u+at
Second equation of motion \(s=ut+\frac{1}{2}at^{2}\)
Third equation of motion v2 = u2+2as






Motion - Class 9th - Physics - Notes






Motion - Class 9th - Physics - Sample Paper