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Potential Energy

Potential energy

Potential energy is the energy that an object possesses due to its position in a force field or that a system has due to the configuration of its parts.

This form of energy is a scalar quantity whose  unit of measurement for the International System of Units is the joule (J).

This  form of energy is associated with the forces acting on a body in such a way that this only depends on the position of the body in space. These forces can be represented by a vector at any point in space, forming what is known as a force vector field or force field.

Definition

If the work of a force field acting on a body moving from a starting position to a final position is determined only by these two positions, and therefore does not depend on the body's path, then there is a function called energy. potential that can be evaluated at both positions to determine the job.

The term potential energy was introduced by nineteenth-century Scottish engineer and physicist William Rankine, although it is related to the Greek philosopher Aristotle's concept of potentiality.

What are the types of potential energy?

The most common types of potential energy are:

  • Gravitational potential energy that depends on the vertical position and the mass of an object.
  • Elastic potential energy of a spring. That the  energy stored in a compressed spring.
  • Electric potential energy of a charge in an electric field.
  • Electrostatic potential energy  .
  • Chemical potential energy.

What is gravitational potential energy?

Gravitational potential energy is the potential energy that an object gains by the gravitational effect of another object (usually very large bodies, for example, the Earth, the Sun). This energy is directly proportional to the mass of the object and the size of the mass attracted. The magnitude of the attracted mass creates the acceleration of gravity. This acceleration for the world is approximately 9.8 m / s² on the surface of the earth.

Gravitational potential energy is equivalent to the  energy required to position an object at a certain height.

Because there are different types of forces, there are also different types of potential energy. Potential energy as a result of the force of gravity.

For example, it is called gravitational energy or potential gravitational energy. For an object with mass m, at height h, the following expression applies to the gravitational energy of the object:

E  = m·g·h

Where (in SI units):

E - The potential energy in joules (J).
m - mass in kilograms (kg)
h - height in meters (m)
g - acceleration of fall in m / s² (approximately 9.81 m / s²)

The gravitational potential energy if the object is on the level. h = 0 is set to zero.

However, when this object is located at a great distance from the earth's surface, gravity is no longer constant and the above formula no longer applies.

The expression of the potential gravitational energy then becomes:

Potential energy

The potential energy at infinite distance from Earth is here at zero, because the formula is the simplest (this is because, unlike in many other cases, the energy difference here has a finite limit). Potential energy is therefore always negative, and as in the model mentioned above, it increases as the object moves away from the earth.

What is elastic potential energy?

Elastic potential energy is energy stored in  a body's ability to  return to its natural position. This form of energy is also called spring energy or potential elastic energy.

The elasticity is a property of certain materials for which a deformed time, drawn or separated from its initial position, can recover their original state, or equilibrium. The recovery forces, when the object recovers its original shape with little damping or deformation, are conservative and an elastic potential energy can be derived, which added to the kinetic energy, allows obtaining the mechanical energy of the object.

A linear (ideal) spring with spring constant k that is drawn (or pushed) at a distance Δl has an increase in spring energy of:

Potential energy

What is chemical potential energy?

Chemical potential energy is related to the structural arrangement of atoms or molecules. This arrangement can be the result of chemical bonds within a molecule or in another way.

The chemical energy of a chemical can be transformed into other forms of energy through a chemical reaction.

Examples of chemical potential energy:

  • When a fuel is burned, chemical energy is converted to heat
  • During the metabolic process of digestion. Food metabolized in a biological organism is transformed into energy.
  • The photosynthesis process. Through this process, green plants transform solar energy into chemical energy.
  • Electrochemical reactions. Electric energy can be converted into chemical energy through electrochemical reactions. These reactions occur during battery charging.

Chemical potential

The chemical potential is used to indicate the potential of a substance to undergo a configuration change . This change can be in the form of a chemical reaction, space transport, exchange of particles with a deposit, etc.

Chemical potential is not a form of potential energy in itself, but is more closely related to free energy. 

How is potential energy transformed into other types of energy?

Energy can manifest in many ways, including:

  • Chemical energy.
  • Thermal energy.
  • Electromagnetic radiation.
  • Gravitational energy.
  • Electric power.
  • Elastic energy.
  • Nuclear energy.
  • Rest energy. 

All of these types of energy can be classified into two main classes: potential energy and kinetic energy. Potential energy can be transferred between objects and transformed into other types of energy.

Potential energy transformation example

Potential energy can be transformed into other types of energy such as kinetic energy, which can be easily illustrated by the following example :

  1. By kicking a ball the player transmits potential energy from his leg to the ball.
  2. This initial energy is converted into elastic potential energy by deforming the balloon and compressing the air inside it.
  3. Upon regaining the original shape, this elastic potential energy is converted into kinetic energy the moment the ball leaves at full speed. All elastic potential energy is energy  transformed into kinetic energy.
  4. If the player has shot the ball with a completely vertical trajectory, as the ball loses speed it will lose kinetic energy, which will be converted into gravitational potential energy .
  5. When you reach the highest point, the ball will have no kinetic energy and all of its energy will be potential.
  6. When the ball begins to drop, the gravitational potential energy turns back into kinetic energy .
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Published: September 1, 2017
Last review: April 2, 2020