A motion will be accelerated when the velocity and acceleration vectors have the same direction. In the case of opposite directions, it is considered as a delayed movement.
Uniformly varied rectilinear motion is characterized as a type of motion in which there is acceleration , that is, the speed of the mobile undergoes variations over time.
According to Newton’s second law , a force causes acceleration in a body, changing its velocity up or down. The directions of the force and acceleration vectors will therefore always be the same.
When velocity and acceleration are in the same direction, the magnitude of velocity increases with time. Because of this, this motion is called accelerated, and these two quantities have the same signs, as shown in the following figure:
When an object is dropped in free fall , in favor of the acceleration of gravity , the motion is also classified as accelerated, because there is an increase in the value of velocity.
When velocity and acceleration are in opposite directions, the magnitude of velocity decreases with time . In this case, this motion is called retarded, and these two quantities have opposite signs. Watch:
When a driver applies the brakes of a car, for example, the movement performed is of the delayed type, as there is a decrease in speed.