Richting van versnellingsvectoren

When an object moves at a constant speed in a straight-line path, it is not involved in an accelerated motion. Instead, it accelerates either by speeding up or by slowing down.

However, on a curved path, even at a constant speed, the object's motion is always accelerated as its direction of motion is changing continuously. Hence, acceleration exists when there is a change in velocity, which can be either due to a  change in speed or change in direction, or both simultaneously.

For an object moving along a curved path with a constant speed, the direction of the acceleration vector is towards the center of the curvature of the path.

When the object speeds up, the acceleration vector points ahead of the center of the curvature. While slowing down, the acceleration points behind the center of the curvature. When the object moves in a straight line, the acceleration is along the path.