Uniform and Non-Uniform Motion along a Straight Line
A body is said to have uniform motion if it covers equal distances in equal intervals of time, no matter however small these time intervals may be. Suppose a car travels at a speed of 25 m/s, it will cover a distance of 25 m every second. Its motion is therefore uniform. It shows that the speed of the object always remains constant and the change in speed is zero.
A body is said to have non-uniform motion if it covers unequal distances in equal intervals of time or covers equal distances in unequal intervals of time. Suppose a stone is dropped from the terrace of a house. It covers say 4.9 m in the 1st second, 14.7 m in the 2nd second, 24.5 m in the 3rd second, and so on. It appears that in the 1st second it covers a small distance; in the 2nd second it covers a larger distance, etc. So we can say that the motion of a freely falling body is non-uniform.