Question

When is the acceleration of a body is positive, negative and zero?

Answer 1

In vector form , if angle between velocity vector and acceleration vector is less than 90° and greater than 0° then it is positive acceleration and if it is less than 180° and greater than 90° then it is negative acceleration. If there is no acceleration vector then it is called zero acceleration

Step-by-step explanation:

Answer 2

The acceleration is positive when it's in the same direction as that of velocity. It keeps on increasing the velocity. In this case, velocity is not constant.

The acceleration is negative when it is in the direction opposite to that of velocity. It keeps on decreasing the speed of body.

The acceleration is zero when the body moves with a constant velocity in any particular direction.