Potential and Kinetic Energy

Dhristi JEE 2022-24

What is Energy?

Energy is the capacity to do work in physics. It exists in potential, kinetic, thermal, electrical, chemical, nuclear, or other forms. You can connect with the best online learning platform  Vedantu, to get a complete understanding of the topics related to the chapter Energy and download FREE PDF Potential and Kinetic Energy - Different Types, Formula, Solved Numericals, etc.

Potential Energy

Potential Energy definition states that “It is the energy stored that depends on the relative location of the different parts of the system”. In systems with parts that exert forces on each other of a magnitude depending on the configuration or relative position of the parts, Potential Energy arises.

When compressed or extended, spring has more Potential Energy. A steel ball after dropping to Earth has less Potential Energy compared to when lifted above the ground. Potential Energy is capable of doing more work in an elevated role. Potential Energy is a system property and not of an individual body or particle; for example, the system consisting of Earth and the raised ball has more Potential Energy as the two are separated further.

The Potential Energy of an object depends only on its original and final configurations. It is independent of the direction traveled by the objects. If the initial position of the ball is ground level and the final position is 10 m above the ground, in this case of the steel ball and the Earth, the Potential Energy is the same, regardless of how or by what route the ball was lifted. The value of Potential Energy is arbitrary and is proportional to the reference point selection. In the above example, if the initial location was the bottom of a 10 m deep pit, the device would have twice as much Potential Energy.

Different Types of Potential Energy

  • Electrical Potential Energy is the energy stored between the plates of a charged capacitor.

  • Chemical energy, the ability of a substance to work or to produce heat from a change in structure, may be considered as Potential Energy arising from the reciprocal forces between its molecules and atoms.

  • Nuclear energy is a form of Potential Energy as well.

Gravitational Potential Energy

The Potential Energy that a massive object has another massive object due to gravity is Gravitational Potential Energy. When the objects fall towards each other, it is the Potential Energy associated with the gravitational field that is released.

By multiplying the weight of an object by its distance above the reference point, Gravitational Potential Energy near the Earth's surface can be measured.

Inbound structures, such as atoms, where electrons are retained by the electrical force of attraction to nuclei, the zero reference for Potential Energy is such that the distance from the nucleus is not measurable by the electrical force. Bound electrons have negative Potential Energy in this case, and those so far away have zero Potential Energy.


Potential Energy Formula

The Gravitational Potential Energy formula relies on the force that acts on the two objects. The formula for the Gravitational Potential Energy is,

P.E. = m*g*h 

Where m is the mass in kilograms,

g is the acceleration due to gravity(9.8 m/s2 at the earth's surface) and 

h is the height in meters.

The SI unit of measurement of Potential Energy is kg. m2/s2 or Joule(J).

Some examples of Potential Energy include:

  • Compressed or extended spring.

  • A ball raised to some height.

  • Stored water in the Dam.

  • A car parked on the hilltop.

  • An arrow about to be shot.

Kinetic Energy

Kinetic Energy is the form of energy in which the object or a particle is said to be in motion. If the work that transfers energy is done on an object by applying a net force, the object speeds up and thus gains Kinetic Energy.

Kinetic Energy is a property of a moving object or particle which depends not only on its movement but also on its mass. Translation, rotation around an axis, vibration, or some combination of motions can be the form of Kinetic Energy.


Kinetic Energy Formula

Kinetic Energy is directly proportional to the object's mass and its velocity square, which is  K.E. = 1/2*m*v²

Where m is the mass in kilograms,

v is the velocity in m/s.

The SI unit of measurement of Kinetic Energy is the same as Potential Energy which is kg. m2/s2 or Joule(J).

The Relation Between Potential Energy and Kinetic Energy

Kinetic Energy is nothing but a form of converted Potential Energy. Potential Energy can be transformed into the energy of motion such as Kinetic Energy and in turn into other forms, such as electric energy. Thus, through turbines that transform electric generators, water behind a dam flows to lower levels, generating electric energy plus some unusable heat energy resulting from turbulence and friction.

Potential Energy and Kinetic Energy are a form of mechanical energy so that the total energy in gravitational systems can be calculated as a constant.

Some examples of Kinetic Energy include:

  • Windmill.

  • Moving vehicle.

  • Running and Walking.

  • Bullet fired from a gun.

  • An arrow shot from a bow.

  • Cycling.

Solved Numerical on Potential and Kinetic Energy

1. In a running race competition, a student who is weighing 40 Kg is running at 4m/s. Calculate the Kinetic Energy of the student.

Ans: It is given that the weight/mass of the student, m = 40 Kg.

The velocity of a student, v = 4m/s.

Kinetic Energy is given by the formula, K.E.=1/2*m*v²

Substituting the values we get, K.E.= 1/2 * 40 * 4*4 = 320 kg. m2/s2.

Therefore the Kinetic Energy of the student is 320 kg. m2/s2.


2. A water tank of mass 50 Kg is stored at a height of 10m. Calculate the Potential Energy of the tank. Consider the value of acceleration due to gravity(g) = 10 m/s2.

Ans: Given the mass of the tank, m = 50 Kg.

Height = 10m and g = 10 m/s2.

Potential Energy formula is given as P.E. = m*g*h.

Substituting the values we get P.E. = 50*10*10= 5000 kg. m2/s2.

Therefore the Potential Energy of the tank is 5000 kg. m2/s2.

FAQs on Potential and Kinetic Energy

1. What is Energy?

Energy in physics is the quantitative property that must be transferred to an object to operate on the object, or to heat it. For all living beings energy is the fundamental form of living. There are various types of energies. The element of energy on earth is the Sun. Energy is defined as the power or strength to do any kind of physical activity. Therefore it can be said that the ability to do work is known as Energy.


The Law of conservation of energy states that “the energy can neither be created nor be destroyed but it can only be converted from one form to another”. The standard unit of energy is Joule. Vedantu provides you with complete details about this topic to help you to understand it in a better way.

2. What is Potential Energy?

In physics, the energy retained by an object is Potential Energy regardless of its location relative to other objects, stresses within itself, its electrical charge, or other variables.


Types of Potential Energy are :

  • Gravitational Potential Energy: the energy stored in an object because of its height or vertical position. An  Example of Potential Energy can be a book kept on the higher shelf that has a higher level of gravitational Potential Energy than the book that is kept on the lower shelf.

  • Elastic Potential Energy: Energy stored because of the force applied to deform an elastic object is known as elastic Potential Energy. The energy that is formed because of the force is stored until the force is removed and the object recovers to its original shape. The object deformations can be of any form like compressing, stretching, or twisting the object.

  • Chemical Potential Energy: The energy stored in the chemical bonds of the substance is known as chemical Potential Energy. This energy is absorbed and released due to changes in the number of particles in the given species.

  • Electric Potential Energy the energy needed to move a charge against an electric field is known as electric Potential Energy. Examples of Potential Energy are :

    • A nonworking radio tower

    • A turned off black light

3. What is Kinetic Energy?

In physics, an object's Kinetic Energy is the energy it possesses due to its motion. It is defined as the work required to accelerate from rest to the specified velocity of a body of a given mass. Having accumulated this energy through its acceleration, until its speed increases, the body retains this Kinetic Energy.


Types of Kinetic Energy are :

  • Radiant Energy: the energy that travels by waves or particles is known as radiant energy, it is created through electromagnetic waves. Most humans experience this type of energy in the form of heat.
    Examples of Radiant Energy are: 

    • Two forms of energy are received when we turn on an incandescent light bulb, light and heat is generated which is visible; these are the two forms of radiant energies.

    • Sunlight is also radiant energy.

  • Thermal Energy: The energy experienced in the form of heat and warmth is called thermal energy. It is similar to radiant energy, thermal energy describes the level of activity among the atoms and molecules in an object but in radiant energy, we refer to waves and particles.
    Examples of thermal energy are :

    • While heating a pizza in the oven, we raise the temperature of the pizza. The molecule that makes up pizza moves faster when the pizza is piping hot. 

    • When the engine emits warmth it is an example of thermal energy.

  • Sound Energy: Sound is the vibrations that reach our ears. The vibrations move in the form of the wave through the medium of air to reach our eardrums. Once they reach then they are converted to electrical signals and then it is sent to the brain where we interpret the sensation of sound.

  • Electrical Energy: When around a circuit there is a flow of negatively charged electrons which results in electricity, which is known as electrical energy.

  • Mechanical Energy: the energy produced by the mechanical movements of the objects is called mechanical energy.

4. What is Energy Conversion?

Energy that is transferred and transformed is called conversion of energy. We all know that energy can be transferred from one form to another is called the transfer of energy. We can notice various energy transformations which are taking place around us.

Energy can be transferred in four ways :

  • By the action of force that is mechanically

  • By electricity that is electrically

  • By the mode of light waves or sound waves that is by radiation

  • By conduction, convection, or radiation that is by heating.

Energy transformation is the process by which the energy is changed from one form to another. The total amount of energy does not change when the energy is transferred or transformed, which is known as energy conservation.

5. Where can I find the best study material for chapter Energy?

Energy is a very important chapter which helps you to score good marks in exams. There are many important topics covered under this chapter which students should prepare well in order to get ready for the examination. 

 

To get the best study material for this chapter students can rely on Vedantu, which is the #1 online learning portal which provides you 100% accurate study material free of cost. You can easily download the free PDF for the revision notes and important questions of chapter Energy which are prepared by the expert team of Vedantu. The team of Vedantu has top-notch teachers that have years of experience to provide the best study material to students to help them to score well in examinations.

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