State the nature of the graphs representing motions of a body with uniform velocity, with uniform acceleration and with uniform retardation respectively in a dispalcement - time graph.

Explanation

In a displacement - time graph, the slope of the graph = rate of displacement with time
= velocity of the body. For a body moving with uniform velocity, velocity = constant. Hence, the slope of the graph is constant. And its displacement - time graph is a straight line [line 1 in ]. In case of motion with uniform acceleration velocity increases and hence the slope of the graph also increases. Line 2 in represents this motion. This line is a parabola. On the other hand in case of motion with uniform retardation the velocity decreases. Line 3 in represents this motion. This line is also a parabola.