What is the relation between distance and time:
$(i)$ when a body is moving with uniform velocity?
$(ii)$ when a body is moving with variable velocity?

(N/A) $(i)$ When a body moves with uniform velocity,the distance covered is directly proportional to the time taken $(s \propto t)$. This results in a linear graph.
$(ii)$ When a body moves with variable velocity,the distance covered is not directly proportional to the time taken. The rate of change of distance with respect to time is non-constant,resulting in a non-linear graph.