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I Made Gatot Karohika , ST. MT. Mechanical Engineering Udayana University

STATIKA STRUKTUR. I Made Gatot Karohika , ST. MT. Mechanical Engineering Udayana University. I. Pendahuluan. Genap 2012-2013. Contents. What is Mechanics? Fundamental Concepts Fundamental Principles Systems of Units Method of Problem Solution Numerical Accuracy.

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I Made Gatot Karohika , ST. MT. Mechanical Engineering Udayana University

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  1. STATIKA STRUKTUR I Made GatotKarohika, ST. MT. Mechanical Engineering UdayanaUniversity I. Pendahuluan Genap 2012-2013

  2. Contents What is Mechanics? Fundamental Concepts Fundamental Principles Systems of Units Method of Problem Solution Numerical Accuracy

  3. ApakahMekanikaitu? • Mekanikaadalahilmu yang menggambarkandanmeramalkankondisibenda yang diamataubergerakkarenapengaruhgaya yang beraksipadabenda. • Categories of Mechanics: • Rigid bodies • Statics • Dynamics • Deformable bodies • Fluids : Compressible dan Incompressible F. (hidrolika) • Mekanikabukanlahsuatuilmu yang abstrakataumurni, tetapisuatuilmuterapan- akantetapimekanikatidakberdasarpadakaidahempirissperti yang terdapatpadailmuteknik lain; pendekatanlebihdititikberatkanpadacaradeduktif yang menyerupaipendekatanmatematika . • Mekanikamerupakandasardaribanyakilmu-ilmuteknikdanmerupakanprasyarat yang tidakdapatdihilangkanuntukmempelajarinya.

  4. Fundamental Concepts • Space [Ruang]– kedudukansuatutitik P. posisititik P dapatdidefinisikandengan 3 jarakdiukurdarisuatutitikacuan/ asal, dalam 3 arah yang ditentukan. Jarakinidikenalsebagaikoordinattitik P • Time[Waktu]– definisidariperistiwamemerlukanspesifikasiwaktudanposisidimanaituterjadi. • Mass [Massa] – digunakanuntukmenentukandanmembedakanbendaatasdasarsuatupercobaanmekanika , e.g., 2 bendadgnmassaygsama, akanditarikolehbumidgncaraygsama; keduabendatsbjgakanmenunjukkansifathambatanygsamaketikamengalamiperubahangeraktranslasi • Force [Gaya] – menunjukkanaksisuatubendaterhadapbenda lain. Gaya ditentukanolehtitikaksinya, besarnya,danarahnya; gayadinyatakansbgsuatuvektor In Newtonian Mechanics, space, time, and mass are absolute concepts, independent of each other. Force, however, is not independent of the other three. The force acting on a body is related to the mass of the body and the variation of its velocity with time.

  5. Newton’s Second Law: bilagayaresultan yang beraksipadasuatupartikeltidaksamadengannol, partikeltersebutakanmemperolehkecepatansebandingdenganbesarnyagayaresultandandalamarah yang samadenganarahgayaresultantersebut • Parallelogram Law • Newton’s Law of Gravitation: duapartikelakansalingtarikmenarik yang samadanberlawanangaya, • Principle of Transmissibility Fundamental Principles • Newton’s First Law: bilagayaresultan yang beraksipadasuatupartikelsamadengannol, partikeltersebutakantetapdiam (apabilamula-muladiam) atauakanbergerakdengankecepatansamapadasuatugarislurus (apabilamula-mulabergerak) 2 buahgayaygberaksipadasuatuparikeldapatdigantidengansebuahgaya, disebutgayaresultan, ygdiperoleh dg menggambarkan diagonal jajarangenjangdgnsisikeduagayatersebut • Newton’s Third Law: Gaya aksidanreaksiantarabenda yang berhubunganmempunyaibesardangarisaksi yang samadanberlawananarah Kondisikeseimbanganataugeraksuatubendategartidakakanberubahapabilagayaygberaksipadasuatutitikdigantidengangaya lain yang samabesardanarahnya, tetapiberaksipadasuatutitkygberbeda , asalkankeduagayaresebutterletakpadasuatugarisaksi yang sama

  6. International System of Units (SI):The basic units are length, time, and mass which are arbitrarily defined as the meter (m), second (s), and kilogram (kg). Force is the derived unit, • Three of the kinetic units, referred to as basic units [satuandasar], may be defined arbitrarily. The fourth unit, referred to as a derived unit [satuanturunan], must have a definition compatible with Newton’s 2nd Law, • U.S. Customary Units:The basic units are length, time, and forcewhich are arbitrarily defined as the foot (ft),second (s), and pound (lb). Mass is the derived unit, Systems of Units • Kinetic Units [satuankinetik]: length [panjang], time [waktu], mass [massa], and force [gaya].

  7. Method of Problem Solution • Problem Statement [PerumusanMasalah]: Includes given data, specification of what is to be determined, and a figure showing all quantities involved. • Solution Check: - Test for errors in reasoning by verifying that the units of the computed results are correct,- test for errors in computation by substituting given data and computed results into previously unused equations based on the six principles,- always apply experience and physical intuition to assess whether results seem “reasonable” • Free-Body Diagrams [Diagram Benda Bebas]:Create separate diagrams for each of the bodies involved with a clear indication of all forces acting on each body. • Fundamental Principles:The six fundamental principles are applied to express the conditions of rest or motion of each body. The rules of algebra are applied to solve the equations for the unknown quantities.

  8. Numerical Accuracy [ ketelitiannumerik] • Ketelitianpenyelesaiansuatusoaltergantungpada 2 hal : 1) ketelitian data yang diberikan,2) ketelitianperhitungan yang dilakukan. Jawabansoaltersebuttidakakanlebihtelitidarikeduahaldiatas. • Penggunaankalkulakortangandankomputermembuatketelitiandariperhitunganlebihbesardariketelitian data . Karenanyaketelitianjawabanbiasanyadibatasiolehketelitian data. • Dalampermasalahanketeknikansecaraumum data mempunyaiketelitiankira-kira 0,2 %. Sehingga , biasanyapendekatanpencatan parameter dimulaidengan“1” dengan 4 digits dandengan 3 digits padakasus yang lain, i.e., 40.2 lb and 15.58 lb. • Kesepakatandikelas: empat digit atau 2 digit dibelakangkomauntukdesimal

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