Question

Q.Clear the confusion that acceleration of a uniform velocity is 0(Line which is parallel to x axis) and the acceleration is above 0 also when there is uniform velocity(straight line) ?

Answer 1

Acceleration is the rate of change of velocity. i.e change in velocity with respect to time(see equation at the end.)

In the first case for a straight line parallel to x axis. At two points in y axis (representing time), x co ordinate is same i.e no change in velocity, hence acceleration is zero for constant uniform velocity.

In second case the velocity at two points on y axis are not same hence does not become zero, when subtracted, hence we say that acceleration is positive and not zero.
Acceleration a = (v2 - v1)/(t2 - t1)

Hope this helps :)