What is Energy?

Energy in physics or chemistry, defined as an ability which transformed, produced, or doing work. From various natural facts of science, energy is different types like kinetic, potential, thermal, electrical, mechanical, internal, chemical, nuclear power, electromagnetic spectrum, surface tension, etc. The first law of thermodynamics conservation of energy defines, energy can neither be created nor be destroyed but it may transfer one form to another.

What is heat energy?

Heat or specific heat is another form of energy that produces work and transferred from one body to another. But heat is different from other sources of energy like chemical, mechanical or electrical because all the other forms completely converted into work but heat can not be wholly converted into work. Another facts of heat energy in learning chemistry or physics, when two objects with different temperatures come together, heat transit or flows from lower temperatures to higher temperatures.

Kinetic and Potential Energy

Energy like kinetic, potential forms in physics, is the ability to transformed produced heat or doing thermal, mechanical types of work in science

What is kinetic energy?

It is the type of energy produced due to the motion of objects. It can be defined and calculated by accelerating a given mass of the body from rest to appropriate speed. It is mainly three types rotational, vibrational, and translational. In classical mechanics, if the mass of the non-rotating body = m and speed of the body in a given time = v. Then the kinetic energy formula = mv2/2. The accelerating bodies maintain their KE unless their velocity changes.

What is potential energy?

The potential energy (PE) formula in science was described first in 19th-century Scottish engineer and physicist William Rankine to define various forms of potential energies held by an object. Gravitational, elastic, electric potential energy are the common types of PE. The common examples of PE are displacing the spring from its equilibrium position, lifting the weight, turning the blades in the wheel. Gravitational potential energy can be calculated by the formula, PEg = mgh, where m = mass of body whose height = h and g = gravity of earth = 9.80665 m/s2.

Types of energy sources

Primary sources are two types, non-renewable and renewable energy sources. Non-renewable sources included nuclear power and fossil fuel like oil, coal, and natural gas or hydrocarbon. Wind, solar, geothermal, hydropower and biogas are examples of renewable sources. These primary sources are converted to electricity, a secondary source, and transmitted to homes and factories.

Renewable or alternative energy comes from sources like sunlight, wind, hydroelectric, geothermal power and, biomass

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What is renewable energy? Renewable energy or alternative energy comes from renewable sources like sunlight (solar energy), wind (wind power), rivers water (hydroelectric power), hot...

For the more precise meaning of work and energy, we recall some relevant examples like combustion or burning of coal or natural gas produces heat. It ultimately enables the engine to work. The mechanical work spent by rubbing two crystalline solid blocks of ice generates a quantity of heat. Therefore, there has an intimate relation between heat, and work, one can yield the other quantity. It is an extensive thermodynamics property like volume or surface area because it depends on the mass of the system. On the other hand, intensive properties like temperature, pressure, density, refractive index, etc are independent of the mass of the system.

Units of heat, energy, and work

Physical quantities other than base physical quantities are called derived physical quantities. The units and dimensions of heat, energy, and work may be expressed in terms of base physical quantities by multiplication and division. From the definition of work, W = F × s, where the force (F) = maas × acceleration and acceleration = length sec-2. Hence, W = mass length2 sec-2.

Unit of work
Quantity SI system CGS system
Work, heat, or energy kg m2 sec-2 or erg g cm2 sec-2 or joule

The ability to doing work is called energy. Therefore, the units and dimensions of work, energy, and heat are the same. The most used unit for heat and energies are calories, kilocalories, eV, liter-atmosphere, etc.

Heat and work

Heat is another form of energy converted into all the other forms like electrical, chemical, mechanical, kinetic, or potential by producing work. The relation between heat and work is the origin of the first law of thermodynamics. It states that if or whenever heat is obtained from work, the amount of heat produced is proportional to work spent. In another word, if heat is transferred into work, there is a proportionality between the work obtained and heat disappeared.

Conversion of heat into work

Heat cannot be completely converted into work because any attempt to convert whole heat into work permanently changes the system or neighboring system. Another facts for learning chemistry or physics, when two objects with different temperatures come together, one with a higher temperature losses heat, and the other gains it.

Types of energy conversion

The production or conversation of heat into work going through a definite process, for example, when a liquid molecule freezes into solid yielding heat or water freezes into ice producing specific heat.

Electrical to mechanical

The electricity that passes through a circuit may produce the rotation of the armature of a motor used for lifting a weight or winding a spring. Conversely, the mechanical work done on the turbine blades of a hydroelectric power plant would generate electricity. These two examples suggest the conversion of electrical to mechanical energy or vice versa.

Chemical to electrical

Redox reaction between chemical elements zinc and copper sulfate produces a large amount of heat. The same chemical change is carried out in Daniell cell or battery for conversion of electrical energy.

What is internal energy?

In thermodynamics, every system has within itself a quantity of energy is called internal energy. It can be obtained by common observations,

  • A liquid freezes into solid yielding heat.
  • Zinc and copper sulfate in Daniell cell producing electricity.
  • Steam expands from a higher to a lower pressure yielding work or mechanical work.
  • Yellow phosphorus glows in oxygen producing light.
  • Carbon monoxide unites with oxygen to producing carbon dioxide and heat energy.

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