Gaya

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Gaya mindeng digambarkeun salaku dorongan atawa tarikan. Dorongan atawa tarikan ieu bisa dibalukarkeun ku fénomena saperti gravitasi, magnétisme, atawa hal séjén anu ngabalukarkeun hiji obyék gerak tambah gancang atawa tambah laun.
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Dina fisika, gaya téh nyaéta tarikan atawa dorongan anu bisa ngabalukarkeun hiji obyék nu boga massa diakselerasi (gerak tambah gancang atawa tambah laun).[1] Gaya boga badag jeung arah tujuan, anu ngajadikeun gaya salaku kuantitas véktor. Nurutkeun Hukum gerak Newton kadua, hiji obyék kalayan massa nu tetep bakal diakselerasi (tambah gancang atawa tambah laun gerakna]] proporsional jeung gaya beresih (néto) anu nimpah kana éta obyék sarta babanding tibalik jeung massana. Gaya anu nimpah kana obyék tilu diménsi bisa ogé ngabalukarkeun obyék kasebut muter atawa ngalaman deformasi, atawa ngahasilkeun parobahan tekenan. Kacondongan hiji gaya pikeun ngabalukarkeun puteran (akselerasi sudut) sabudeureun hiji sumbu disebut torsi. Deformasi jeung tekenan mangrupakeun hasil tina gaya-gaya strés dina jero hiji obyék.[2][3]

Panneau travaux.png Artikel ieu keur dikeureuyeuh, ditarjamahkeun tina basa Inggris.
Bantosanna diantos kanggo narjamahkeun.

Since antiquity, scientists have used the concept of force in the study of stationary and moving objects. These studies culminated with the descriptions made by the third century BC philosopher Archimedes of how simple machines functioned. The rules Archimedes determined for how forces interact in simple machines are still a part of physics.[4] Earlier descriptions of forces by Aristotle incorporated fundamental misunderstandings which would not be corrected until the seventeenth century by Isaac Newton.[3] Newtonian descriptions of forces remained unchanged for nearly three hundred years.

Current understanding of quantum mechanics and the standard model of particle physics associates forces with the fundamental interactions accompanying the emission or absorption of gauge bosons. Only four fundamental interactions are known: in order of decreasing strength, they are: strong, electromagnetic, weak, and gravitational.[2] High-energy particle physics observations made during the 1970s and 1980s confirmed that the weak and electromagnetic forces are expressions of a unified electroweak interaction.[5] Einstein in his theory of general relativity explained that gravity is an attribute of the curvature of space-time.

Pre-Newtonian concepts[édit | sunting sumber]

Aristotle famously described a force as anything which causes an object to undergo "unnatural motion"

Since antiquity, the concept of force has been recognized as integral to the functioning of each of the simple machines. The mechanical advantage given by a simple machine allowed for less force to be used in exchange for that force acting over a greater distance. Analysis of the characteristics of forces ultimately culminated in the work of Archimedes who was especially famous for formulating a treatment of buoyant forces inherent in fluids.[4]

Aristotle provided a philosophical discussion of the concept of a force as an integral part of Aristotelian cosmology. In Aristotle's view, the natural world held four elements that existed in "natural states". Aristotle believed that it was the natural state of objects with mass on Earth, such as the elements water and earth, to be motionless on the ground and that they tended towards that state if left alone. He distinguished between the innate tendency of objects to find their "natural place" (e.g., for heavy bodies to fall), which led to "natural motion", and unnatural or forced motion, which required continued application of a force.[6] This theory, based on the everyday experience of how objects move, such as the constant application of a force needed to keep a cart moving, had conceptual trouble accounting for the behavior of projectiles, such as the flight of arrows. The place where forces were applied to projectiles was only at the start of the flight, and while the projectile sailed through the air, no discernible force acts on it. Aristotle was aware of this problem and proposed that the air displaced through the projectile's path provided the needed force to continue the projectile moving. This explanation demands that air is needed for projectiles and that, for example, in a vacuum, no projectile would move after the initial push. Additional problems with the explanation include the fact that air resists the motion of the projectiles.[7]

These shortcomings would not be fully explained and corrected until the seventeenth century work of Galileo Galilei, who was influenced by the late medieval idea that objects in forced motion carried an innate force of impetus. Galileo constructed an experiment in which stones and cannonballs were both rolled down an incline to disprove the Aristotelian theory of motion early in the seventeenth century. He showed that the bodies were accelerated by gravity to an extent which was independent of their mass and argued that objects retain their velocity unless acted on by a force, for example friction.[8]

Newtonian mechanics[édit | sunting sumber]

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 Artikel utama: Newton's laws of motion.

Isaac Newton is the first person known to explicitly state the first, and the only, mathematical definition of force—as the time-derivative of momentum: \vec{F} = \frac{\mathrm{d}\vec{p}}{\mathrm{dt}}. In 1687, Newton went on to publish his Philosophiae Naturalis Principia Mathematica, which used concepts of inertia, force, and conservation to describe the motion of all objects.[3][9] In this work, Newton set out three laws of motion that to this day are the way forces are described in physics.[9]

Though Sir Isaac Newton's most famous equation is F=ma, he actually wrote down a different form for his second law of motion that used differential calculus.

References[édit | sunting sumber]

  1. "glossary". Earth Observatory. NASA. Diakses pada 9 April 2008. "Force: Any external agent that causes a change in the motion of a free body, or that causes stress in a fixed body." 
  2. a b e.g. Feynman, R. P., Leighton, R. B., Sands, M. (1963). Lectures on Physics, Vol 1, Addison-Wesley.; Kleppner, D., Kolenkow, R. J. (1973). An introduction to mechanics, McGraw-Hill..
  3. a b c University Physics, Sears, Young & Zemansky, pp18–38
  4. a b Heath,T.L.. "The Works of Archimedes (1897). The unabridged work in PDF form (19 MB)". Archive.org. Diakses pada 14 Oktober 2007. 
  5. Kesalahan pengutipan: Tag <ref> tidak sah; tidak ditemukan teks untuk ref bernama final_theory
  6. Land, Helen The Order of Nature in Aristotle's Physics: Place and the Elements (1998)
  7. Hetherington, Norriss S. (1993). Cosmology: Historical, Literary, Philosophical, Religious, and Scientific Perspectives, Garland Reference Library of the Humanities.
  8. Drake, Stillman (1978). Galileo At Work. Chicago: University of Chicago Press. ISBN 0-226-16226-5
  9. a b Newton, Isaac (1999). The Principia Mathematical Principles of Natural Philosophy, Berkeley: University of California Press. This is a recent translation into English by I. Bernard Cohen and Anne Whitman, with help from Julia Budenz.

Bibliography[édit | sunting sumber]

  • Corbell, H.C., Philip Stehle (1994). Classical Mechanics p 28,, New York: Dover publications. ISBN 0-486-68063-0.
  • Cutnell, John d., Johnson, Kenneth W. (2004). Physics, Sixth Edition, Hoboken, NJ: John Wiley & Sons Inc..
  • Feynman, R. P., Leighton, R. B., Sands, M. (1963). Lectures on Physics, Vol 1, Addison-Wesley. ISBN 0-201-02116-1.
  • Halliday, David, Robert Resnick; Kenneth S. Krane (2001). Physics v. 1, New York: John Wiley & Sons. ISBN 0-471-32057-9.
  • Parker, Sybil (1993). Encyclopedia of Physics, p 443,, Ohio: McGraw-Hill. ISBN 0-07-051400-3.
  • Sears F., Zemansky M. & Young H. (1982). University Physics, Reading, MA: Addison-Wesley. ISBN 0-201-07199-1.
  • Serway, Raymond A. (2003). Physics for Scientists and Engineers, Philadelphia: Saunders College Publishing. ISBN 0-534-40842-7.
  • Tipler, Paul (2004). Physics for Scientists and Engineers: Mechanics, Oscillations and Waves, Thermodynamics, 5th ed., W. H. Freeman. ISBN 0-7167-0809-4.
  • Verma, H.C. (2004). Concepts of Physics Vol 1., 2004 Reprint, Bharti Bhavan. ISBN 81-7709-187-5.

Tumbu luar[édit | sunting sumber]