KULIAH I                            MEKANIKA TEKNIK TI                              PENDAHULUAN              OLEH:        ...
Apa itu Mekanika?      Cabang ilmu fisika yang berbicara tentang      keadaan diam atau geraknya benda-benda      yang men...
Buku apa yang dipakai?• R. C. Hibbeler, Engineering Mechanics, 7 th - 10th  Edition, Person Prentice-Hall• F. P. Beer and ...
Bagaimana evaluasinya ?           • Tugas-Kuis : 25 %           • UTS        : 30 %           • UAS        : 45 %Tidak men...
Penjelasan TUGAS• Dikerjakan pada kertas A4• Tulis nama dan NRP di sebelah kanan atas,  serta tanggal dan tugas ke berapa•...
Apa saja yang dipelajari?• Keseimbangan partikel• Keseimbangan benda tegar• Diagram gaya normal, diagram gaya  geser, dan ...
Apa pentingnya mekanika (statik) /        keseimbangan ?
Apa perbedaan partikel dan benda tegar?• Particle: A very small amount of matter which  may be assumed to occupy a single ...
Apa perbedaan Partikel dan Benda Tegar ? Partikel:              Benda Tegar: Mempunyai suatu        Kombinasi sejumlah mas...
Contoh Partikel
Contoh Benda Tegar
Review Sistem Satuan• Four fundamental physical quantities. Length, Time, Mass, Force.• We will work with two unit systems...
Apa yang harus dilakukan supaya         Mekanika Teknik menjadi mudah ?Banyak dan sering menyelesaikan soal-soalProsedur m...
THE WHAT, WHY AND HOW OF A         FREE BODY DIAGRAM (FBD)Free Body Diagrams are one of the most important things foryou t...
How ?1. Imagine the particle to be isolated or cut free from its   surroundings.2. Show all the forces that act on the par...
Fundamental Principles• The parallelogram law for the addition of forces: Two  forces acting on a particle can be replaced...
Fundamental Principles (cont’)• The principle of transmissibility: A force acting at a point  of a rigid body can be repla...
APPLICATION OF VECTOR      ADDITION            There are four            concurrent cable forces            acting on the ...
Addition of Vectors                • Trapezoid rule for vector addition                • Triangle rule for vector addition...
Sample Problem                                  SOLUTION:                                  • Trigonometric solution - use ...
Sample Problem (cont’)       • Trigonometric solution - Apply the triangle rule.         From the Law of Cosines,         ...
ADDITION OF SEVERAL VECTORS            • Step 1 is to resolve each force            into its components            • Step ...
Example of this   process,
You can also represent a 2-D vector with a          magnitude and angle.
EXAMPLE                               Given: Three concurrent forces                                      acting on a brac...
EXAMPLE (continued)F1 = { 15 sin 40° i + 15 cos 40° j } kN   = { 9.642 i + 11.49 j } kNF2 = { -(12/13)26 i + (5/13)26 j } ...
EXAMPLE (continued)Summing up all the i and j components respectively, we get,FR = { (9.642 – 24 + 31.18) i + (11.49 + 10 ...
Sample Problem                                       SOLUTION:                                       • Resolve each force ...
Sample Problem (cont’)        SOLUTION:        • Resolve each force into rectangular            force mag           compon...
READING QUIZ1. The subject of mechanics deals with what happens to a body   when ______ is / are applied to it.  A) magnet...
READING QUIZ3. Which one of the following is a scalar quantity?    A) Force B) Position C) Mass D) Velocity4. For vector a...
CONCEPT QUIZ5. Can you resolve a 2-D vector along two directions, which   are not at 90° to each other?   A) Yes, but not ...
ATTENTION QUIZ7. Resolve F along x and y axes and write it in   vector form. F = { ___________ } N                        ...
205 wikarta-kuliah i mektek ti
Upcoming SlideShare
Loading in...5
×

205 wikarta-kuliah i mektek ti

494

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
494
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
66
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide
  • Mainly explain the three steps using the example .
  • Answers: 1.C 2.A
  • Answers: 1. C 2. D
  • Answers: 1. C 2. A
  • Answers: 1. C 2. C
  • 205 wikarta-kuliah i mektek ti

    1. 1. KULIAH I MEKANIKA TEKNIK TI PENDAHULUAN OLEH: ALIEF WIKARTA, STJURUSAN TEKNIK MESIN, FTI – ITS SURABAYA, 2007
    2. 2. Apa itu Mekanika? Cabang ilmu fisika yang berbicara tentang keadaan diam atau geraknya benda-benda yang mengalami kerja atau aksi gaya Mechanics Rigid Bodies Deformable Bodies Fluids(Things that do not change shape) (Things that do change shape) Statics Dynamics Incompressible Compressible
    3. 3. Buku apa yang dipakai?• R. C. Hibbeler, Engineering Mechanics, 7 th - 10th Edition, Person Prentice-Hall• F. P. Beer and E. R. Johnston Jr., Vector Mechanics for Engineers: Statics, SI Metric Edition, Mcgraw-hill, 3rd Edition• R. C. Hibbeler, Mechanics of Material, 3th Edition, Person Prentice-Hall• dll
    4. 4. Bagaimana evaluasinya ? • Tugas-Kuis : 25 % • UTS : 30 % • UAS : 45 %Tidak mentolerir segala bentuk kecurangan Tapi tetap boleh cross check
    5. 5. Penjelasan TUGAS• Dikerjakan pada kertas A4• Tulis nama dan NRP di sebelah kanan atas, serta tanggal dan tugas ke berapa• Silahkan mengerjakan soal apa saja yang berkaitan dengan materi yang disampaikan• Silahkan mengerjakan berapa pun soal yang sanggup anda selesaikan• Soal-soal harus dari buku yang disepakati• Mencantumkan judul buku, pengarang, dan nomer soal yang dikerjakan, plus halaman buku
    6. 6. Apa saja yang dipelajari?• Keseimbangan partikel• Keseimbangan benda tegar• Diagram gaya normal, diagram gaya geser, dan diagram momen• Konsep tegangan• Momen inersia dan momen polar• Teori kegagalan statis
    7. 7. Apa pentingnya mekanika (statik) / keseimbangan ?
    8. 8. Apa perbedaan partikel dan benda tegar?• Particle: A very small amount of matter which may be assumed to occupy a single point in space.• Rigid body: A combination of a large number of particles occupying fixed position with respect to each other.
    9. 9. Apa perbedaan Partikel dan Benda Tegar ? Partikel: Benda Tegar: Mempunyai suatu Kombinasi sejumlah massa namun partikel yang mana ukurannya dapat semua partikel diabaikan, sehingga berada pada suatu geometri benda tidak jarak tetap terhadap akan terlibat dalam satu dengan yang lain analisis masalah
    10. 10. Contoh Partikel
    11. 11. Contoh Benda Tegar
    12. 12. Review Sistem Satuan• Four fundamental physical quantities. Length, Time, Mass, Force.• We will work with two unit systems in static’s: SI & US Customary. Bagaimana konversi dari SI ke US atau sebaliknya ?
    13. 13. Apa yang harus dilakukan supaya Mekanika Teknik menjadi mudah ?Banyak dan sering menyelesaikan soal-soalProsedur mengerjakan soal:1. Baca soal dengan cermat2. Buat free body diagram dan tabulasikan data soal3. Tuliskan prinsip dasar / persamaan yang relevan dengan soal4. Selesaikan persamaan sepraktis mungkin sehingga didapat hasil yang signifikan dan jangan lupa disertai sistem satuan5. Pelajari jawaban dengan akal sehat, masuk akal atau tidak6. Jika ada waktu, coba pikirkan cara lain untuk menyelesaikan soal tersebut.
    14. 14. THE WHAT, WHY AND HOW OF A FREE BODY DIAGRAM (FBD)Free Body Diagrams are one of the most important things foryou to know how to draw and use.What ? - It is a drawing that showsall external forces acting on theparticle.Why ? - It helps you write theequations of equilibrium used tosolve for the unknowns (usuallyforces or angles).
    15. 15. How ?1. Imagine the particle to be isolated or cut free from its surroundings.2. Show all the forces that act on the particle. Active forces: They want to move the particle. Reactive forces: They tend to resist the motion.3. Identify each force and show all known magnitudes and directions. Show all unknown magnitudes and / or directions as variables . A Note : Engine mass = 250 Kg FBD at A
    16. 16. Fundamental Principles• The parallelogram law for the addition of forces: Two forces acting on a particle can be replaced by a single force, called resultant, obtained by drawing the diagonal of the parallelogram which has sides equal to the given forces f1+f2 f2 f1 • Parallelogram Law
    17. 17. Fundamental Principles (cont’)• The principle of transmissibility: A force acting at a point of a rigid body can be replaced by a force of the the same magnitude and same direction, but acting on at a different point on the line of action f2 f1f1 and f2 are equivalent if their • Principle of Transmissibilitymagnitudes are the same and theobject is rigid.
    18. 18. APPLICATION OF VECTOR ADDITION There are four concurrent cable forces acting on the bracket. How do you determine the resultant force acting on the bracket ?
    19. 19. Addition of Vectors • Trapezoid rule for vector addition • Triangle rule for vector addition • Law of cosines, CB R 2 = P 2 + Q 2 − 2 PQ cos B    C R = P+Q • Law of sines, sin A sin B sin C = = B Q R A • Vector addition is commutative,     P+Q = Q+ P • Vector subtraction
    20. 20. Sample Problem SOLUTION: • Trigonometric solution - use the triangle rule for vector addition in conjunction with the law of cosines and law of sines to find the resultant.The two forces act on a bolt atA. Determine their resultant.
    21. 21. Sample Problem (cont’) • Trigonometric solution - Apply the triangle rule. From the Law of Cosines, R 2 = P 2 + Q 2 − 2 PQ cos B = ( 40 N ) 2 + ( 60 N ) 2 − 2( 40 N )( 60 N ) cos155° R = 97.73N From the Law of Sines, sin A sin B = Q R Q sin A = sin B R 60 N = sin 155° 97.73N A = 15.04° α = 20° + A α = 35.04°
    22. 22. ADDITION OF SEVERAL VECTORS • Step 1 is to resolve each force into its components • Step 2 is to add all the x components together and add all the y components together. These two totals become the resultant vector. • Step 3 is to find the magnitude and angle of the resultant vector.
    23. 23. Example of this process,
    24. 24. You can also represent a 2-D vector with a magnitude and angle.
    25. 25. EXAMPLE Given: Three concurrent forces acting on a bracket. Find: The magnitude and angle of the resultant force. Plan:a) Resolve the forces in their x-y components.b) Add the respective components to get the resultant vector.c) Find magnitude and angle from the resultant components.
    26. 26. EXAMPLE (continued)F1 = { 15 sin 40° i + 15 cos 40° j } kN = { 9.642 i + 11.49 j } kNF2 = { -(12/13)26 i + (5/13)26 j } kN = { -24 i + 10 j } kNF3 = { 36 cos 30° i – 36 sin 30° j } kN = { 31.18 i – 18 j } kN
    27. 27. EXAMPLE (continued)Summing up all the i and j components respectively, we get,FR = { (9.642 – 24 + 31.18) i + (11.49 + 10 – 18) j } kN = { 16.82 i + 3.49 j } kN y FRFR = ((16.82)2 + (3.49)2)1/2 = 17.2 kNφ = tan-1(3.49/16.82) = 11.7° φ x
    28. 28. Sample Problem SOLUTION: • Resolve each force into rectangular components. • Determine the components of the resultant by adding the corresponding force components. • Calculate the magnitude and directionFour forces act on bolt A as shown. of the resultant.Determine the resultant of the forceon the bolt.
    29. 29. Sample Problem (cont’) SOLUTION: • Resolve each force into rectangular force mag components. x − comp y − comp  F1 150 + 129.9 + 75.0  F2 80 − 27.4 + 75.2  F3 110 0 − 110.0  F4 100 + 96.6 − 25.9 R x = +199.1 R y = +14.3 • Determine the components of the resultant by adding the corresponding force components. • Calculate the magnitude and direction. R y 14.3 N tan α = = α = 4.1° α = 4.1° Rx 199.1 N 14.3 N R= = 199.6 N sin α
    30. 30. READING QUIZ1. The subject of mechanics deals with what happens to a body when ______ is / are applied to it. A) magnetic field B) heat C) forces D) neutrons E) lasers2. ________________ still remains the basis of most of today’s engineering sciences. A) Newtonian Mechanics B) Relativistic Mechanics C) Euclidean Mechanics C) Greek Mechanics
    31. 31. READING QUIZ3. Which one of the following is a scalar quantity? A) Force B) Position C) Mass D) Velocity4. For vector addition you have to use ______ law. A) Newton’s Second B) the arithmetic C) Pascal’s D) the parallelogram
    32. 32. CONCEPT QUIZ5. Can you resolve a 2-D vector along two directions, which are not at 90° to each other? A) Yes, but not uniquely. B) No. C) Yes, uniquely.6. Can you resolve a 2-D vector along three directions (say at 0, 60, and 120°)? A) Yes, but not uniquely. B) No. C) Yes, uniquely.
    33. 33. ATTENTION QUIZ7. Resolve F along x and y axes and write it in vector form. F = { ___________ } N y A) 80 cos (30°) i - 80 sin (30°) j x B) 80 sin (30°) i + 80 cos (30°) j C) 80 sin (30°) i - 80 cos (30°) j 30° F = 80 N D) 80 cos (30°) i + 80 sin (30°) j8. Determine the magnitude of the resultant (F1 + F2) force in N when F1 = { 10 i + 20 j } N and F2 = { 20 i + 20 j } N . A) 30 N B) 40 N C) 50 N D) 60 N E) 70 N
    1. A particular slide catching your eye?

      Clipping is a handy way to collect important slides you want to go back to later.

    ×