# What is acceleration? Acceleration: Concept, Formula and Examples

## What is acceleration?

We explain what acceleration is and the formulas used to calculate it. In addition, its difference with speed and examples.

The concept of acceleration comes from Isaac Newton’s mechanical studies.

We call acceleration in physics a vector magnitude (i.e., one endowed with direction) that indicates the variation in velocity according to the passing of time of a moving object.

It is normally represented by the sign a and its unit of measurement in the International System is m/s2 (meters per second squared).

The origin of acceleration as a concept comes from the mechanical studies of Isaac Newton (founders of classical mechanics), in which it is assured that an object will keep its rectilinear and uniform movement (M.R.U.) unless forces leading to acceleration act on it, either positive (increase in speed) or negative (decrease in speed), and either constant (regulate in its action on the body) or not (irregular in its action on the body).

### There are several types of acceleration:

• Positive acceleration. When it takes place in the same direction as the path of motion, adding to the speed of motion.
• Negative acceleration. When it takes place in the opposite direction of the path of movement, opposing the speed of this movement.
• Medium acceleration. Average of the accelerative movement of a mobile in time, whenever it occurs in regular units of increase or decrease (uniformly accelerated movement).

### Acceleration Formula

Classical mechanics understands acceleration as a variation of the velocity of a body in time, so it proposes the following formula: a = dV / dt, where a will be acceleration, dV the difference of velocities and dt the time in which acceleration occurs.

Both variables are understood in the following way:

• dV = Vf – Vi, where Vf will be the final speed and Vi the initial speed of the mobile. It is important to observe this order to reflect the direction of acceleration.
• dt = tf – ti, where tf will be the end time and ti the initial time of the movement. Unless otherwise stated, the initial time will always be 0 seconds.

On the other hand, according to Newton’s studies, given a body of constant mass (m), there is a relationship of proportionality with respect to the force applied to the object (F) and the acceleration obtained from it (a), and that is how it is posed:

F = m.a

That way, we can calculate the acceleration with the following formula:

a = F / m

All this according to Newton’s second Law or Fundamental Law of Dynamics.

## Speed and acceleration

Acceleration has to do with the variation of speed in an object.

Speed and acceleration are two different concepts. Its difference is that the former refers to the amount of distance a body travels in a given unit of time (so it is measured in Kmph, for example) while acceleration has to do with the variation of that velocity in an object, whether it moves or not (Initial velocity = 0).

## Examples of acceleration

Some examples of acceleration might be:

• The launch of a space rocket, which gains speed as it ascends. It is possible to calculate its acceleration if we have the force of the thrust that its fuel provides and the total mass of the rocket.
• A train that stops, experiences a negative acceleration when it is about to approach the station, which can be calculated using the initial and final speeds corresponding to each passing instant.

A ball is resting on the ground before a child kicks it. The ball will reach a certain speed in its displacement, after it has accelerated from 0 to that average speed and then decelerate again until it returns to rest.

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