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Force

From Simple English Wikipedia, the free encyclopedia

For the Star Wars term, seeThe Force.

Inphysics, aforce is a push or pull or a twist betweenobjects. It is called aninteraction because if one object acts on another, itsaction ismatched by areaction from the other object.^[1] This idea is known asNewton's third law,^[2] whereaction andreaction are "equal and opposite"^[3] (matched).Theobjects are just the things the force acts between. Different forces act between different sorts of objects. For example,gravity acts between objects withmass, like thesun and theearth. Another example iselectromagnetic force, which acts between objects withcharge, like anelectron and thenucleus of anatom.Gravity andelectromagnetic force are two examples of forces.

A force changes the state of an object (somephysical quantity changes) or, strictly, the states of two objects, since the force is an interaction. For example, a force causes an affected object to be pushed or pulled in a certain direction. This changes the object'smomentum. Forces cause objects toaccelerate, add to the object's overallpressure,change direction, orchange shape. Because themagnitude anddirection of a force are both important, force is avector quantity. The strength of a force is measured in newtons (N). There are fourfundamental forces inphysics.

A force is always a push, pull, or a twist, and it affects objects by pushing them up, pulling them down, pushing them to a side, or by changing their motion orshape in some other way.

Newton's Second Law

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According toNewton's Second Law of Motion, the formula for finding force is:

F=ma

where $F {\displaystyle F}$ is the force,
$m {\displaystyle m}$ is themass of an object,
and $a {\displaystyle a}$ is theacceleration of the object.

His second law definesa force to be equal to change in momentum (mass times velocity) per change in time. Momentum is defined to be the mass m of an object times its velocity V.

Weight

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Gravity is an acceleration. Everything that has a mass is being pulled toward the Earth because of that acceleration. This pull is a force called weight.

One can take theequation above and change $a {\displaystyle a}$ to the standardgravityg, then a formula about the gravity on earth can be found:

W=mg

where $W {\displaystyle W}$ is theweight of an object,
$m {\displaystyle m}$ is the mass of an object,
and $g {\displaystyle g}$ is the acceleration due to gravity atsea level. It is about $9.8m/s^{2}$ .

This formula says that when you know the mass of an object, then you can calculate how much force there is on the object because of gravity.You must be on earth to use this formula. If you are on the moon or another planet, then you can use the formula butg will be different.

Force is avector, so it can be stronger or weaker and it can also point in differentdirections.Gravity always points down into the ground (if you are not in space).

Gravitational force

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Another equation that says something about gravity is:

{F}={\frac {Gm_{1}m_{2}}{d^{2}}}

$F {\displaystyle F}$ is force; $G {\displaystyle G}$ is thegravitational constant, which is used to show how gravity accelerates an object; $m_{1}$ is the mass of one object; $m_{2}$ is the mass of the second object; and $d {\displaystyle d}$ is the distance between the objects.

This equation is used to calculate how the earth moves around the sun and how the moon moves around the earth. It is also used to calculate how other planets, stars and objects in space move around.

The equation says that if two objects are very heavy then there is a strong force between them because of gravity.If they are very far apart then the force is weaker.

The four forces of the Universe

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Objects and particles in theUniverse interact. How the particles and object interact is governed by four forces of nature. They are:

TheFermilab in the U.S. is aparticle accelerator. They are investigating results which suggest a possible fifth force of nature.^[4]

References

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↑"Any single force is only one aspect of a mutual interaction betweentwo bodies."(Halliday, Resnick& Krane 2001, pp. 78–79) harv error: no target: CITEREFHallidayResnickKrane2001 (help)
↑C. Hellingman (1992). "Newton's third law revisited".Phys. Educ.27 (2):112–115.Bibcode:1992PhyEd..27..112H.doi:10.1088/0031-9120/27/2/011.S2CID 250891975.Quoting Newton in thePrincipia: It is not one action by which the Sun attracts Jupiter, and another by which Jupiter attracts the Sun; but it is one action by which the Sun and Jupiter endeavour (try) to come nearer together.
↑Newton, Isaac (1687).Philosophiae Naturalis Principia Mathematica (in Latin).contrariam semper & aequalem
↑BBC News: Scientists at Fermi Lab close in on fifth force of nature.

Further reading

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Gravity

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