Suppose there are 2 cars
Car 1 and Car 2
Both Car cover a distance of 80 km
Car 1 Covers 40 km in first hour and 40 Km in second hour
Car 2 Covers 30 km in First Hour and 50 Km In Second Hour
It is said that
Car 1 is in Uniform Motion
Car 2 is in Non Uniform Motion
What is Uniform Motion?
A body is in uniform motion if it covers equal distance in equal intervals of time
Example
Car 1 travelling at 40 km in both first and second hour
What is Non Uniform Motion?
A body is in non uniform motion if it covers unequal distance in equal intervals of time
Example
Car 1 travelling at 30 km in first hour and 50 km in second hour
Note
Non Uniform Motion is also called Accelerated Motion
Note
Graph of Uniform Motion is Straight LineGraph of Non  Uniform Motion is Curved Line
In Uniform Motion, Equal Distance is Traveled even over Small Distances
Note
If a body travels at a uniform speed,it means it travels equal distance at equal intervals of time.
It does not matter how small these intervals of time are.
Example
Suppose a train travels 120 kilometer in 1 Hour in uniform motion
It means ,it travels at a uniform speed
In 60 Minutes = 120 Km
In 1 Minutes = 120/60 = 2 Km
In 60 Seconds = 2000 m
I 1 Second = 2000/60 = 33.33 meter
Difference between uniform and nonuniform motion
Uniform Motion  Non Uniform Motion 
It has zero acceleration. 
It has nonzero acceleration.

Distancetime graph shows a straight line 
Distancetime graph shows a curved line

Covers equal distances in equal time interval. 
Covers unequal distances in equal time interval.

Its average speed is same as speed of the object 
Its average speed is different as speed of the object

Questions
Q 4 Page 102  What does the path of an object look like when it is in uniform motion?