A positive acceleration means an increase in velocity with time. negative acceleration means the speed reduces with time. its a retardation. If the speed is increasing, the car has positive acceleration. When the car slows down, the speed decreases. When an object is speeding up, the acceleration is in the same direction as the velocity. Thus, this object has a positive acceleration.
- Acceleration is a vector quantity as it has both magnitude and direction. It is also the second derivative of position with respect to time or it is the first derivative of velocity with respect to time.
Positive and negative acceleration
When an item moves in a positive direction (left to right) and the rate of change of velocity is positive, we call it positive acceleration (velocity is increasing). When an item moves in a positive direction, the acceleration is negative, but the rate of change in velocity is negative (velocity is decreasing).Similarly, the rate of change of velocity decreases in the negative direction is considered positive acceleration as it implies increasing the speed in a positive direction.