gravitypotential energyGravitational potential energy refers to the energy possessed by an object due to gravity.The gravitational potential energy of an object at a certain point in space is equal to making the object move from that point toReference point(i.e. a specificlevel）The work done by gravity.The formula of gravitational potential energy: Ep=mgh.
Potential energy: potential energy is the energy of interacting objects by virtue of their relative positions.
The energy of an object due to being lifted is called gravitational potential energy.Under special circumstancesGravitational potential energyIt is the generalization ofspatial location The determined energy is related to the reference point selected to determine its spatial position.The gravitational potential energy of an object at a certain point in space is equal to the work done by gravity when the object moves from that point to the reference point (i.e. a specific horizontal plane).
determinant
The gravity potential energy of an object is determined by the gravity of the earth on the object and the relative position of the earth and the object on the ground.The larger the mass, the higher the position, and the greater the ability to do work, the more gravitational potential energy the object has.
To some extent, when the height is fixed, the greater the mass, the greater the gravitational potential energy;When the mass is constant, the higher the height, the greater the gravitational potential energy
So we get the definition of gravitational potential energy
Where r is the distance from the object to the center of the earth.
Understanding of the minus sign: When an object is moved from infinity to the center of the force applying body by gravity, gravity does work and the potential energy decreases.
To judge whether an object has gravitational potential energy, the key is to see whether the object is raised relative to a plane, that is, whether it has a certain height relative to the plane.If there is, then the object has gravitational potential energy; if there is no, then the object does not have gravitational potential energy.
In physics, the magnitude of the gravitational potential energy of an object isMass of objectIt is proportional to the height of the object being lifted.
So it is concluded that Ep=mgh.
The gravitational potential energy isscalarInjoule(J)。Unlike Gong, GongSignIndicates the effect of the action. When comparing the size, only the numerical value is compared;But gravitypotential energyinPositive numberThey are always greater than negative numbersexpressionSince the height h is relative, the value of gravitational potential energy is also relative.We say that an object has gravitational potential energy mgh, which is relative to a certain horizontal plane. If the height of this horizontal plane is taken as zero, this horizontal plane is calledReference planeWhen the object is on this reference plane, the gravitational potential energy is zero, so the reference plane is also called the zero potential energy plane.Classical physicsThe understanding of gravitational potential energy is that when an object is in a position, relative to the reference plane, how much work can gravity do to the object, and how much other forms of energy can the object obtain, that is, how much gravitational potential energy is.But it doesn't mean that if the gravitational potential energy is 0, there is noWorkThe ability ofRelativityDetermined.GravityPositive workWhen gravity does negative work, the gravitational potential energy increases.
Two objects are only affected byUniversal gravitationThe gravitational potential energy of mutual attraction: the process of two objects attracting each other only by universal gravitation is actually very complicated. FirstTwo body problem(The problem that two objects move due to gravity) is transformed into a single body problem (the problem that one object moves due to the gravity of another fixed object, and the transformation method isgeneral physics The textbook and the textbook of theoretical physics and mechanics are included)Rectilinear motionThe process ofKepler's third lawSolve.In addition, if the pre collisionInstantaneous velocityYou can use it firstMomentum conservationDetermine the speed ratio of two objects before collision, and thenConservation of mechanical energyFind out the speed at the time of collision, but this method requires that the objects being collided are spheres of size. Otherwise, if they are only regarded as particles, the gravitational potential energy at the moment before collision will be negative infinity.
If g is considered as a variable, then the gravitational potential energy will transition toGravitational potential energyThe expression of gravitational potential energy is - GMm/r, but the zero potential energy is at infinity.
Object due tomechanical movementThe energy possessed is calledmechanical energy。Including kinetic energy andpotential energyTwo, potential energy includes gravitational potential energy andElastic potential energySince gravity and universal gravitation are forces of the same nature, it is more appropriate to call gravitational potential energy gravitational potential energy when the height of an object cannot be ignored, that is, gravitational potential energy is gravitational potential energy. In the outline, except that gravity changes with the position (latitude and height) of an object on the earth, gravity is considered equal to universal gravitation,Therefore, it can also be considered that the gravitational potential energy of an object is equal to the gravitational potential energy.
The gravitational potential energy is relative, but the variation of gravitational potential energy isAbsoluteness。That is to say, the gravitational potential energy willReference planeHowever, the change amount of gravitational potential energy will not change due to the difference of reference plane.
characteristic
The work done by gravity has nothing to do with the path, but only with the position of the starting point and the end point[1]。
Gravity potential energy and gravity work
When gravity does positive work, the gravitational potential energy decreases;When gravity does negative work, the gravitational potential energy increases;It can be understood that the work done by gravity is equal to the negative value of the change of gravitational potential energy, namely:
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Work done by gravity
Gravitational potential energy
Physical meaning
Work done by gravity on objects
Energy determined by the relative position between objects and the earth due to their interaction
expression
Ep=mgh
Factors affecting size
Height difference △ h between gravity G and initial and final positions
Gravity mg and height of a position h
characteristic
It is only related to the height difference between the initial and final positions
Selection of path and reference plane is independent
Related to the selection of reference plane, objects at the same position
Process quantity
State quantity
potential energy
Announce
edit
definition
When driving piles, lift the heavy hammer high. When the heavy hammer falls, the wooden pile can be driven into the ground.Heavy hammer can do work because it is lifted. The energy of lifted object is called gravitational potential energy.Mass of objectThe larger it is, the higher it is lifted, the greater the gravitational potential energy it has.The weight being lifted has gravitational potential energy.The greater the weight of the hammer, the higher it is lifted and the more work it does when falling, which means the greater the gravity potential energy of the hammer.(Not all lifts are artificial, but the height rising relative to the horizontal plane is the height to be lifted)
Archer's bowStretch bendingAfter letting go, the bent bow can shoot the arrow.The compressed spring can lift the weight on it after it is relaxed.Bow and spring are caused byElastic deformationThe energy of the elastic deformation object that can do work is called elastic potential energy.The greater the elastic deformation of an object, the greater its elastic potential energy.
category
Potential energy is divided into gravitational potential energy, elastic potential energyMolecular potential energy、Electric potential energy, gravitational potential energy, etc.Potential energy is infinite energy.
[Gravitational Potential Energy] is the energy possessed by an object due to gravity, and the formula is Ep=mgh (m is the mass, g should be 9.8N/kg (in most cases), h is the height of the object from the horizontal plane)
[Molecular potential energy]It's intermolecularInteraction forceAnd the energy generated,Molecular forceDivided intorepulsionAnd gravity.stayBalance positionThe molecular force is repulsive when it is smaller than the equilibrium position, and gravitational when it is larger than the equilibrium position.But no matter when, gravity and repulsion exist at the same time.
[Electric potential energy]Electric potential energy refers to the position determined energy of electric charge due to the action of electric field in electric field.
In fact, there is a certain relationship between the potential energy Ep and the force F, distance h (elastic potential energy is x, gravitational potential energy is r, etc.), that is, d (Ep)/dh=F.It can also be written as Ep=∨ Fdh, bothConservatismWhat has been doneWork。
The potential energy is aScalar functionWhen an object shares potential energy or multiple potential energies with multiple objects, the total potential energy of the object is the algebraic sum of all potential energies.
According to the definition, the potential energy depends on the relativity of two or more objectsConfiguration, is the location of two or more objectsshareOf.However, in the conservative system composed of two objects A and B, if we take one object A asReference system, then the potential energy only depends on the relative position of another object B.At this time, without causing confusion, we often refer to "the potential energy of A and B" as "the potential energy of B".For example, the charge in the electric field has electrostatic potential energy, or another object near one object has gravitational potential energy.In addition, sometimes there is only one object in the conservative system, and the potential energy comes from therelative displacement At this time, we also say that the potential energy is possessed by this object.For example, a spring or one with volume distributed chargeinsulatorThe Ball.
It should be noted that even in the sameConservative force fieldAt the same place in, the potential energy of different objects is generally different, for example, in gravityScope of actionThe gravitational potential energy of an object depends not only on its height, but also on its mass.
