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energy(W)
energy f

energy . The energy of a body or system is its ability to perform work. The unit of energy is the joule.

It is useful to talk about different forms of energy. When work is done, energy is transferred from one form to another. (See efficiency) Here are some types:
gravitational potential energy The work that a mass can do by falling a distance W = mghh.

Electrical energy: the work that can be done by the electric current, I, in time W = VIt: t.

Kinetic energy: the work that can be done by a mass m moving quickly, when it rests (stopping): mc2 1/2 = .W.

Kinetic energy: thermal energy: the work necessary for a mass m with specific heat capacity to raise C capacity to 0 degrees: W = mco.

A = potential → kinetic attraction
B = Kinetic → Rotation, Rotation → Electrical
C = electrical → optical + thermal

Other names used include elastic potential energy, latent heat, mass energy, and chemical energy.

The above diagram shows a series of energy transfers. In each case, the useful power output is less than the total input. All of these chains are really long.


energy, law of conservation of energy loif de conservation de l'énergie

Law of conservation of energy. This basic law of physics says that energy is conserved and cannot be created or destroyed.

In any energy transfer, the useful energy output is less than the total input. (See efficiency). Here the law of energy conservation also applies and the rest of the energy income is wasted, meaning it appears in a less useful form.

engineering
generation f

engineering . The field in which pure science concepts are applied to real-life problems. Branches of engineering that rely mainly on physics include:

* Aeronautical engineering, which is the technology of air and space flight.

* Civil engineering is concerned with the design of bridges, roads, large buildings, and other public use structures.

* Electrical and electronic engineering » electrical and electronic engineering deals with strong and weak electrical currents.

* Marine engineering, the design of ships and how they operate and behave.

* Mechanical engineering, the use of machines of all types.

* Nuclear engineering, which deals with all nuclear power systems.


engines
motorsmpl

Engines are systems in which the chemical energy (potential) of fuel is converted into mechanical energy (work). The fuel burns in oxygen, producing a huge volume of hot gas. The expansion of this gas leads to the transfer of energy into the system.

Steam engines are combustion engines
External combustion engines, where the fuel burns outside the place where the work evaporates. In steam exchange engines, hot steam expands against a piston in a cylinder. Steam turbines have fans rotated by hot gas.

“Internal combustion engines” are also these two categories, except that the fuel in these engines burns where the work is done, that is, in the cylinder or turbine chamber. All internal combustion engines operate in four stages, and the following drawing shows these stages for the four-stroke engine, which runs on petrol. Most cars run.

A) “Intake”: A mixture of air and petroleum vapor enters the chamber through an inlet valve when the piston descends.

b) “Compression”: The piston rises and compresses the mixture forcefully (the two valves are closed).

C) “Power: A spark ignites the plug causes the fuel to ignite in the air, and the resulting hot gases push the piston down.

d) “Exhaust”: The piston rises and pushes the burning gases out through the exhaust valve.

Diesel engines, jet engines, and rocket engines are all internal combustion engines.