With the help of a graph, derive the relation v = u + at.

**Answer:**

Consider the velocity-time graph of an object that moves under uniform acceleration as shown in the figure

From this graph, we can see that initial velocity of the object (at point A) is u and then it increases to v (at point B) in time t. The velocity changes at a uniform rate a. As shown in the figure, the lines BC and BE are drawn from point B on the time and the velocity axes respectively, so that the initial velocity is represented by OA, the final velocity is represented by BC and the time interval t is represented by OC. BD = BC - CD, represents the change in velocity in time interval t.