=The definition of acceleration is a change in the rate of motion, speed or action
=A positive acceleration means an increase in velocity with time. negative acceleration means the speed reduces with time. ... When the car slows down, the speed decreases. When an object is speeding up, the acceleration is in the same direction as the velocity.

What is acceleration?

Acceleration is a fundamental concept in physics that describes how quickly an object's velocity changes over time. It is defined as the rate of change of velocity. Velocity, in turn, is the rate of change of an object's displacement.

Positive Acceleration

Positive acceleration occurs when an object's velocity increases over time. This means that the object is moving faster and faster in a particular direction. It is represented by a positive value.

Negative Acceleration

Negative acceleration, also known as deceleration or retardation, occurs when an object's velocity decreases over time. This means that the object is slowing down in a particular direction. It is represented by a negative value.

Explanation

Acceleration can be understood by considering the concept of velocity. Velocity is a vector quantity that includes both magnitude (speed) and direction. When an object accelerates, its velocity changes. This change can occur in magnitude, direction, or both.

When an object's velocity increases, it experiences positive acceleration. This can happen when an object speeds up, such as a car accelerating from rest or a sprinter running faster and faster. Positive acceleration can also occur when an object changes direction without changing speed, like a car turning a corner.

On the other hand, negative acceleration occurs when an object's velocity decreases. This can happen when an object slows down, such as a car braking or a ball thrown upwards coming to a stop and falling back down. Negative acceleration can also occur when an object changes direction while slowing down, like a car decelerating while turning.

It is important to note that positive and negative acceleration are not absolute values. They are relative to a chosen reference point or initial velocity. For example, a car moving at a constant speed of 50 km/h may experience positive acceleration if its speed increases to 60 km/h, but it will experience negative acceleration if its speed decreases to 40 km/h.

In summary, acceleration describes how an object's velocity changes over time. Positive acceleration occurs when velocity increases, while negative acceleration occurs when velocity decreases. These concepts are crucial in understanding the motion of objects and are fundamental in the study of physics.