What is potential energy - definition (2023)

What is potential energy

potential energy, U, is defined as theenergy savedin an object subjected to a conservative force. Common types include thepotential energy of gravity, Dieelastic potential energyan extended spring, and theelectrical potential energyan electric charge in an electric field and so on.

Let's assume thatmechanical energy(E_mech), this is the energy associated with thatMovementAndPositionof an object usually in a force field (e.g. gravitational field).Mmechanical energy(and also thermal energy) can be divided into two categories, transient and stored. Transient energy is energy in motion, ie energy that is transferred from one place to another. Stored energy is the energy contained in a substance or object. Transient mechanical energy is commonly referred to aswork. Stored mechanical energy exists in one of two forms:kineticorpotential:

• potential energy. The potential energy U is defined as the energy stored in an object subjected to a conservative force. Common types include an object's gravitational potential energy, which depends on its mass and its distance from the center of mass of another object.
• Kinetic energy. the kinetic energy,K, is defined as the energy stored in an object due to its motion. It depends on the speed of an object and is the ability of a moving object to work on other objects when colliding with them.

Examples of potential energy

Gravitational Potential Energy:

In classical mechanics, gravitational potential energy (U) is the energy possessed by an object due to its position in a gravitational field. The gravitational potential (V; the gravitational energy per unit mass) at a location is equal to the work (energy transferred) per unit mass that would be required to move the object from a fixed reference location to the object's location. The most common use of gravitational potential energy is for an object near the earth's surface, where the gravitational acceleration can be assumed to be constant at about 9.8 m/s².

U = mgh

Elastic potential energy:

Elastic potential energy is potential energy released as a result of the deformation of an elastic object, such as a B. the elongation of a spring is stored. It depends on the spring constant k and the stretched path.

U = 1/2 kx²

Electrical potential energy:

Electric potential energy is potential energy resulting from conservative Coulomb forces associated with the configuration of a specific set of point charges within a defined system. For example, if a positive charge Q is fixed at a certain point in space, any other positive charge brought close to it will experience a repulsive force and therefore have potential energy.

U = kQq/R

conservation of mechanical energy

First the principle ofconservation of mechanical energywas ascertained:

The total mechanical energy(defined as the sum of its potential and kinetic energies) of a particle on which only conservative forces actis constant.

See also:conservation of mechanical energy

An isolated systemis one in whichno external forcecauses energy changes. If onlyconservative forcesact on an object andUis thepotential energyfunction for the total conservative force, then

E_mech= U + K

The potential energyU, depends on the position of an object subjected to a conservative force.

It is defined as the object's ability to do work and is increased when the object is moved in the opposite direction of the direction of the force.

The potential energyassigned to a system consisting of the earth and a nearby particlepotential energy of gravity.

the kinetic energy,K, depends on the speed of an object and is the ability of a moving object to work on other objects when colliding with them.

K = ½ mv²

The above definition (E_mech= U + K) assumes that the system isfree from frictionand othernon-conservative forces. The difference between a conservative and non-conservative force is that when a conservative force moves an object from one point to another, the work done by the conservative force is independent of the path.

In every real situationfriction forcesand other non-conservative forces exist, but in many cases their impact on the system is so small that the principle ofconservation of mechanical energycan be used as a good approximation. For example, the frictional force is a non-conservative force because it acts to reduce the mechanical energy in a system.

Note that non-conservative forces do not always reduce mechanical energy. A non-conservative force changes the mechanical energy, there are forces that increase the total mechanical energy, such as the force provided by a motor or motor is also a non-conservative force.

Block sliding down a smooth incline

The 1 kg block starts at a height H (let's say 1 m) above the groundpotential energy mgHAndkinetic energythat equals 0. It slides to the ground (with no friction) and arrives with no potential energy and no kinetic energyK = ½ mv². Calculate the speed of the block on the ground and its kinetic energy.

E_mech= U + K = const

=> ½ Mw²= mgH

=> v = √2gH = 4,43 m/s

=>K₂= ½ x 1 kg x (4,43 m/s)²= 19,62 kg.m².S^-2= 19,62 J

Pendulum

Suppose aPendulum(Ball of mass m suspended from a cord of lengthLthat we pulled up so that the ball has heightH<Labove its lowest point on the arc of its stretched string motion. The pendulum is exposed to thisconservative Gravitational forcewhere frictional forces such as drag and friction at the pivot point are negligible.

We free it from the rest.How fast does it go down?

The pendulum is enoughgreatest kinetic energyAndlowest potential energyif invertical position, because at this point it will have the greatest speed and will be closest to the earth. On the other hand, it will have itslowest kinetic energyAndgreatest potential energyIn theextreme positionsof its momentum because it has no speed at those points and it is furthest from Earth.

When the amplitude is limited to small swings, the period isTof a simple pendulum, the time for a complete cycle is:

WoLis the length of the pendulum andGis the local acceleration due to gravity. For small swings, the swing duration is about the same for swings of different sizes. That is,the period is independent of the amplitude.

See also:

Energy