# Where is acceleration directed?

Acceleration is the speed of change in speed. This value is vector, it has its direction and is measured in m / s2(in the SI).

In order to understand where the acceleration vector is directed, it is first necessary to determine what kind of motion the point at which we are following is.

## Types of movement

### If this movement is in a straight line and the speed increases.

The acceleration will be directed to the same direction as the speed. Their vectors will coincide.

### If this movement is in a straight line and the speed decreases.

The acceleration vector will be the opposite of the velocity vector.

### If this movement is in a straight line, the speed does not change.

Acceleration will be zero and will not be sent anywhere.

### Movement along a circle with uniform speed.

If the point moves in a circle and the speed does not change, then the acceleration here is called the centripetal (or normal) and its vector is directed to the center of the circle.

### Movement along a circle with a varying speed.

In this case, there is another acceleration - tangential (or tangential). Itis directed from the point along the tangent to the circle inthe side of the motion, if the speed increases, and in the opposite direction, if the speed decreases. But about the centripetal, too, should not be forgotten. It turns out that the point is affected by 2 types of acceleration. Here we introduce the concept of complete acceleration. Its vector is the bisector of the angle between the vector of the centripetal acceleration and the tangent vector.

Note that at each point of motion along the circumference, the vector of full acceleration will change its direction.

In addition to the direction, the acceleration also has its own magnitude.