What is velocity-time graph of a body? Draw velocity-time graphs for
(i) a body moving with uniform velocity,
(ii) a body moving with uniform acceleration, and
(iii) a body moving with variable acceleration.

Velocity-time graph. It is the graph obtained by plotting velocity of the body along Y-axis and time along X-axis.

(i) Velocity-time graph for uniform velocity. For a body moving with a constant velocity, the velocity-time graph is a straight line parallel to the time-axis, as shown in Fig. (a).

(ii) Velocity-time graph for uniform acceleration. For a body in uniform acceleration, the increase in velocity is proportional to the time taken. So velocity-time graph is a straight line inclined to the time-axis, as shown in Fig. (b).

(iii) Velocity-time graph for variable acceleration. For a body having variable acceleration, the velocity increases by unequal amounts in equal intervals of time. So velocity-time graph is a curve, as shown in Fig.  (c).