Kinetic energy

When a body is in motion we say that it produces or contains kinetic energy, in other words, it is the energy associated with objects that are in motion. Apply force or work on an object that is in a state of rest, sufficient to cause its acceleration and make it move. It is very important to keep in mind that all matter has internal energy, however, in order to give kinetic energy to an object, you must work or use force on it so that it can be set in motion.

what is kinetic energy

It refers to any energy charge that is related to or is the cause of the movement of objects, as in the case of translational kinetic energy and rotational kinetic energy.

From the etymological point of view, the word energy comes from the Greek terms “energeia” and “energós” which mean activity and force of action, respectively. On the other hand, kinetics derives from the Greek “kinesis” which means movement.

As for kinetic and potential energy, the main difference is that the first refers specifically to the movement of an object produced by a force, while the second refers to a static energy that relates the position of an object in relation to another in space. space.

On the other hand, kinetic and potential energy are the general representations of the set of energies that exist on the planet, that is, the rest are derived from one of them or formed by a mixture of both.

Characteristics of kinetic energy

As all energy has a series of its own characteristics, as well as mathematical procedures and calculations that facilitate its understanding and application, all this is achieved through kinetic energy exercises.


Kinetic Energy - Energy calculation with practical example

One of the main properties is the fact that it depends directly on the mass and speed of the object under study, the greater these qualities, the greater the energy. As is known, the application of an external force is necessary for the start.

This type of energy corresponds to a magnitude of measurement of the scalar type and not vectorial as it happens with other areas of physics. It speaks of positive work when it is increasing and negative when it decreases. The direction of movement does not matter.

The intensity of the external force applied to the object at the beginning will directly influence the speed of the object and therefore the amount of kinetic energy that will be produced in the body.

It is important to mention that it has the ability to transform or become other types of energy on its own or in conjunction with potential. Some of the types of energy that derive from this are the following: mechanical, which comes from the sum of both, electrical, caloric, among others.


Through kinetic energy problems, the kinetic energy formula can be applied to determine and know its magnitude in relation to any moving object. This formula is as follows:
Ec= ½ mv²

The energy itself is measured in Joules, the mass in kilograms and the speed in meters over seconds.

Types of Kinetic Energy

There are in principle three types of kinetic energy, each with its own characteristics.

translational kinetic energy

Translational kinetic energy occurs at the moment that all the parts that correspond to or form an object follow the same trajectory or direction, that is, when the movement is carried out linearly in space.
In this case the formula would be:

Ec = 1/2 m V² (V = linear speed)

Rotational Kinetic Energy

In the case of rotational kinetic energy, it occurs when the movement is carried out on the same axis of the body, a characteristic example of this type is the movement of a spinning top. The corresponding formula is:

Erot = 1/2 I ω² (ω = angular velocity)
In which Ix represents the moment of inertia and W is the angular velocity.

molecular kinetic energy

It refers to a theory that specifies that all existing objects are composed of internal molecules and that these molecules are in constant motion, but that the speed and intensity of the movements is directly proportional to the temperature, that is, the higher the temperature, the higher the temperature. movement of internal molecules.

This theory is used to explain, for example, the behavior at the macro level of the different existing gases, indicating that for this observable behavior to be possible, the interaction between the internal molecules that form these gases is necessary and that their interaction will depend directly on the temperature.

Kinetic energy applications

One of the constant applications of this type of energy is achieved thanks to its transformation capacity to generate other types of energy, as is the case of its transformation into heat and electricity, used for example in bicycles.

Due to this discovery in the transportation area worldwide, research and tests are carried out to transform the sufficient quantity into electrical energy that allows the movement of trains, racing cars, among others.

What is intended with this new trend is that most of the objects and machinery that work by means of electricity are capable of creating their own source of energy through kinetics, at present there are more and more pilot plans and projects of this type.

In principle, it is an important part as a source for different daily activities that facilitate life as we know it, for example, travel by plane, car, obtaining drinking water, electricity, among others.

examples of kinetic energy

Kinetic Energy - Example (cyclist in motion by application of force)

A typical example is the case of a glass container that falls into the void, during the fall and thanks to the movement of the body, kinetic energy is accumulated during its trajectory, which is released when it hits the ground and breaks.

Another situation in which not only the kinetic, but also the potential is present is in the case of a young man on a skateboard, when he is on a “U” track, when he stops at the ends, the potential type is presented and When the movement begins, both ascending and descending, the kinetics are presented, the mass of the person and the speed influence the intensity.

At a sports level, this type of energy is present in boxing, although both competitors have similarity in terms of body mass, it is possible that one is faster than the other and therefore that higher speed produces greater intensity and generation of force. .

It also occurs naturally in the environment, such as the detachment of part of a glacier or the collapse of a mountain.

In the case of the roller coaster, both types of energy are presented in the same way, the potential just before starting the journey and once started, the accumulation of kinetic energy begins, the intensity of which will depend on the number of people in the car. .

The most characteristic example is that of the bicycle, not only because of the production of kinetic energy when pedaling, but also because of its transformation into two other types of power, such as electricity and the increase in temperature.

On the other hand, during a ball game, the person throwing it applies a force on it and depending on its intensity, it generates a predetermined speed and in turn the accumulation of energy, which must be counteracted when the other person catches it and activates again when it is returned.

Frequently Asked Questions about Kinetic Energy

What is kinetic energy?

It refers to that which is produced and accumulated thanks to the movement of an object in space, it depends directly on its speed and mass, for its start it is necessary to apply an external force that produces movement.

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How is kinetic energy measured?

Joules (J) are measured.

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What is kinetic energy for?

This has a capacity for transformation into other types of energy, including electricity and heat, due to this there are currently a large number of innovative projects that seek to use it as a source for the operation of the transportation area in general. Functioning as a kind of renewable and ecological energy.

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How to calculate kinetic energy?

The calculation is made through the formula: Ec= ½ mv², in which “m” represents the mass of the moving object and “v” its speed during movement. It will also depend on whether it is translational or rotational, each one presents variations in its formulas.

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What is the difference between kinetic and potential energy?

The main difference is that the kinetic comes from the movement itself, it is generated and accumulated thanks to the displacement of the object in question, while the potential is a type of static energy, coming from the relationship of an object at rest with respect to another.

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