In physics, acceleration is the vector quantity, endowed with direction, which is used to express the way in which a target varies in speed according to the passing of time of an object that is in motion, taking an ascending trajectory.
Acceleration is represented by the sign ” a” and its unit in the International System is m/s2 (meters per second squared).
The origin of acceleration as a concept has its origin in the mechanical studies carried out by Isaac Newton. The founder of classical mechanics ensures that an object maintains its rectilinear and uniform motion unless forces act on it that lead to acceleration. This acceleration can be both positive, if the speed increases, and negative, if it decreases. Furthermore, it can be constant, if it is regular in its action on the body, or not, if it is irregular in its action on it.
According to the above, we can distinguish between different types of acceleration:
- Positive. This type of acceleration is the one that occurs in those cases in which the acceleration takes place in the same direction as the trajectory of the movement. In this way it adds to the speed that the body has.
- Negative. It occurs when the acceleration goes in the opposite direction to the trajectory of the movement, causing it to oppose the speed that the body carries.
- Half. It is the average of the acceleration movement of a mobile in time, as long as it takes place in regular units of increase or decrease (uniformly accelerated movement).
Acceleration formula
In classical mechanics, acceleration is understood as the variation in velocity of a body over time. This causes the formula a = dV / dt to be used. In it, “a” is the deceleration; «dV», the difference between the speeds; and “dt” the time in which the acceleration occurs.
In this way, both variables are understood in this way:
- dV = V f – V i : In it «Vf» is the final velocity and «Vi», the initial velocity. Attention must be paid to the order to know the direction of acceleration.
- dt = t f – t i : In This “tf” is the final time and “ti” the initial time of the movement. Unless otherwise stated, the initial time will always be 0 seconds.
Likewise, it must be taken into account that, according to Isaac Newton and his studies, given a body of constant mass (m), there is a proportional relationship with respect to the force of the objective (F) and the acceleration that can be obtained from it. (a). That is, F = ma
In this way, the acceleration m can be calculated as follows: a = F/m.
In this, Newton’s second Law or Fundamental Law of Dynamics is taken into account.
Speed and acceleration
It is important to be able to distinguish between velocity and acceleration, since they are two different concepts. However, it is common to make the mistake of confusing both.
The difference is that speed refers to the amount of distance that a body can travel in a given unit of time. Acceleration, for its part, is the variation of the speed of an object, regardless of whether it is moving or not (in which case the initial speed is 0).
Types of acceleration
There are different types of acceleration. In this sense we find tangential acceleration, which is what relates the variation of speed with time. On the other hand there is also the normal (or centripetal) acceleration. This is responsible for linking changes in direction over time.
In addition we also find the average speed. Calculates the average change in speed in a given time interval.
In addition, it must be taken into account that the acceleration can have different directions. In this way, the acceleration can be both in the direction of the speed itself and in the opposite direction, as we have explained previously.
Acceleration examples
Some examples of acceleration can be the following:
- A train, when it stops, has a negative acceleration when it is close to the station. To do this, its initial and final speed can be calculated, corresponding to each instant.
- When a space rocket takes off, since it manages to have more speed as it manages to ascend. Acceleration can be calculated by counting the thrust force provided by the fuel, as well as knowing the total mass of the rocket.
- In the event that a ball is at rest on the ground before being kicked. The ball will be able to reach a certain speed when moving. Therefore, it will accelerate from 0 to maximum speed, and then slow down until it returns to a state of rest.