Persamaan Gelombang bunyi periodik Sifat-sifat Gelombang Bunyi A STUDY IN SOLID GEOMETRY Polyhedra Eko Nursulistiyo 1

Bunyi These are the Five Platonic Solids   Now, each of the solids have planes or flat surfaces.  These flat surfaces are called faces but I do not like to word face as others apply it.  I like the word surface better because when I think of the word face I picture that an object has a front and a back with the front being the face.  When you rotate or turn a flat surface on a polyhedra perpendicular to your nose, that becomes its new "face" therfore its new front.   So, I make a feeble effort to try to eliminate this confusion by using the word surface.  Even though I use the words point, apex, and vertex redundantly here, actually a point on a geometric solid is called a vertex for the singular and vertices for the plural.

Persamaan periodik gelombang bunyi. TETRAHEDRON: The word "Tetra" is a Greek word and it has something to do with the number "four."  Now, with a tetrahedron you have an equileteral triangle as its base.  Then you place an equilateral triangle at each edge of the base then they all come up to a point, apex, or vertex if you will.  So, with "tetra" meaning "four",  you have four surfaces.  The tetrahedron was also associated somehow with "Fire" in Plato's day. These are the Five Platonic Solids. Now, each of the solids have planes or flat surfaces. These flat surfaces are called faces but I do not like to word face as others apply it. I like the word surface better because when I think of the word face I picture that an object has a front and a back with the front being the face. When you rotate or turn a flat surface on a polyhedra perpendicular to your nose, that becomes its new "face" therfore its new front. So, I make a feeble effort to try to eliminate this confusion by using the word surface. Even though I use the words point, apex, and vertex redundantly here, actually a point on a geometric solid is called a vertex for the singular and vertices for the plural.

Persamaan periodik gelombang bunyi. HEXAHEDRON: This is your standard cube, but "Hex" comes from the Greek meaning "six."  About the only fascinating thing about this solid is that when you rotate it to where a point, apex, or vertex is perpendicular to your nose, you should notice that the outer edges form a "hexagon."  And, this solid was associated with the "Earth" for some reason. Now, when this solid is constructed as a frame, without welding or solder, it is very unstable.  The "Earth" is a very unstable thing because of its volcanoes and earthquakes. TETRAHEDRON: The word "Tetra" is a Greek word and it has something to do with the number "four." Now, with a tetrahedron you have an equileteral triangle as its base. Then you place an equilateral triangle at each edge of the base then they all come up to a point, apex, or vertex if you will. So, with "tetra" meaning "four", you have four surfaces. The tetrahedron was also associated somehow with "Fire" in Plato's day.

Bunyi OCTOHEDRON: "Octo" means "eight" in the Greek.  I describe this solid as if you would take two pryamids and glue the basses squarely together, therefore creating "eight" surfaces if you will.  Now, the fascinating thing about this solid is that when you rotate or turn a point, apex, or vertex perpendicular to your nose you are looking at a "top" of a pryamid.  And, in Plato's day this was associated with "Air" somehow! HEXAHEDRON: This is your standard cube, but "Hex" comes from the Greek meaning "six" so this solid has six surfaces. About the only fascinating thing about this solid is that when you rotate it to where a point, apex, or vertex is perpendicular to your nose, you should notice that the outer edges form a hexagon. And, this solid was associated with the "Earth" for some reason. Now, when this solid is constructed as a frame, without welding or solder, it is very unstable. The "Earth" is a very unstable thing because of its volcanoes and earthquakes.

Persamaan periodik gelombang bunyi. DODECAHEDRON: Now, in the Greek the "Do" means "two" and the "Deca" equals "ten", so, we have the number "twelve."  So, it is constructed of "twelve" Pentagons in a ball shape.  This solid is associated  with what was known at the time as "The Æther" or the Universe.  It was also associated somehow with "Spirit."  As with the Hexahedron, this solid is also unstable because when this is constructed as a frame, here again, without welding or solder, not all of the pentagons retain their shape.  And, what can be more unstable that the Spirit of Man.  Almost as unstable as the Earth. OCTOHEDRON: "Octo" means "eight" in the Greek. I describe this solid as if you would take two pryamids and glue the basses squarely together, therefore creating eight surfaces if you will. Now, the fascinating thing about this solid is that when you rotate or turn a point, apex, or vertex perpendicular to your nose you are looking at a "top" of a "pryamid." And, in Plato's day this was associated with "Air" somehow!

Sifat Gelombang Bunyi Syarat -syarat terjadinya bunyi 1. ada sumber bunyi, 2. ada medium perantara, dan 3. ada pendengar (penerima bunyi). Frekuensi Bunyi Nada Cepat rambat bunyi ICOSAHEDRON: "Icosa" comes from the Greek and it has something to do with the number "twenty" somehow.  This solid is constructed of "twenty" equalateral triangles in a ball shape and it was associated with "Water" somehow. DODECAHEDRON: Now, in the Greek the "Do" means "two" and the "Deca" equals "ten", so, we have the number "twelve." So, it is constructed of "twelve" Pentagons in a ball shape. This solid is associated with what was known at the time as "the $ther" or the Universe. It was also associated somehow with "Spirit." As with the Hexahedron, this solid is also unstable because when this is constructed as a frame, here again, without welding or solder, not all of the pentagons retain their shape. And, what can be more unstable that the Spirit of Man. Almost as unstable as the Earth.

Frekuensi 1. Gelombang Infrasonik Gelombang infrasonik adalah gelombang yang mempunyai frekuensi di bawah jangkauan manusia, yaitu lebih kecil dari 20 Hz. Gelombang infrasonik hanya mampu didengar oleh beberapa binatang seperti jangkrik, anjing, dan kelelawar. 2. Gelombang Audiosonik Gelombang audiosonik adalah gelombang yang mempunyai frekuensi antara 20 sampai 20.000 Hz. Gelombang audiosonik merupakan gelombang yang mampu didengar oleh pendengaran manusia dan sebagian besar binatang. 3. Gelombang Ultrasonik Gelombang ultrasonik mempunyai frekuensi di atas jangkauan pendengaran manusia, yaitu lebih besar dari 20.000 Hz. Kelelawar pada malam hari memancarkan gelombang ultrasonik dari mulutnya. Gelombang ini akan dipantulkan kembali bila mengenai benda. Dari gelombang pantul yang didengar tadi, kelelawar dapat mengetahui jarak dan ukuran benda yang berada di depannya. Q? and A. Well, any? ICOSAHEDRON: "Icosa" comes from the Greek and it has something to do with the number twenty somehow. This solid is constructed of twenty equalateral triangles in a ball shape and it was associated with "Water" somehow.

Frekuensi Gelombang ultrasonik dimanfaatkan oleh manusia dalam berbagai bidang, antara lain: a. untuk mengukur kedalaman air laut, b. untuk sterilisasi pada makanan, c. digunakan dalam bidang kedokteran untuk memeriksa tubuh manusia (ultrasonografi) d. kacamata tunanetra. e. meratakan campuran logam pada industri logam f. meratakan campuran susu agar homogen pada pabrik susu g. alat kontrol jarak jauh (remote control) pada televisi Facilitator! dajerutneusa@hotmail.com ICOSAHEDRON: "Icosa" comes from the Greek and it has something to do with the number twenty somehow. This solid is constructed of twenty equalateral triangles in a ball shape and it was associated with "Water" somehow.

Nada Nada = frekuensi beraturan Desah = frekuensi tidak beraturan Bunyi pantul memperkuat bunyi asli Gaung atau kerdam Gema

Cepat rambat bunyi Menghitung jarak kilat dari kita Kecepatan bunyi dalam medium berbeda-beda

Cepat rambat bunyi Medium Cepat rambat bunyi (m/s) Gas karbon 267 Udara pada suhu 0º C 332 Udara pada suhu 15º C 340 Udara pada suhu 25º C 347 Hidrogen 1.286 Alkohol 1.213 Timbal 1.300 Air pada suhu 15º C 1.440 Emas 2.030 Aluminium 5.000 Baja 5.100 Besi 5.120 Kaca 4.000 - 5.500 Granit 6.000

Cepat rambat bunyi

Soal Berapakah nada C, G, E jika nada A berada pada 440 Hz? Bunyi guntur terdengar 3 detik setelah terlihat petir, jika kecepatan bunyi di udara 340 m/s berapakah jarak pendengar ke kilat tersebut?

Soal Sebuah kapal laut dengan peralatan SONAR mengirimkan gelombang ultrasonik ke dasar laut dan menerimanya kembali setelah 5 detik. Jika cepat rambat bunyi di dalam air laut 1440 m/s, berapakah kedalaman laut tersebut? Seorang anak berteriak k e dalam sumur yang kosong, selang waktu 0,4 s dia mendengar bunyi pantulnya. Jika cepat reambat bunyi di udara 340 m/s berapakah kedalaman sumur?