Question

give an example to show that direction of velocity of a body can change even when its acceleration is constant

Answer 1

Yes..this is possible if we rotate a stone in a circular path. Here speed and acceleration remains constant BUT the velocity changes at every instant..since the direction is always perpendicular to axis. So to attain its perpendicular line, it changes its direction every time.

Answer 2

An object undergoing a constant acceleration has a constantly changing velocity. If the acceleration always points in the same direction as the velocity, the trajectory will be no different than if there were no acceleration.