Gelombang Longitudinal
Gelombang adalah getaran yang merambat pada suatu medium atau tanpa
medium dengan tidak disertai perambatan bagian-bagian medium itu
sendiri.
Gelombang longitudinal adalah
gelombang yang arah getarannya sejajar dengan arah rambat gelombang.
Serangkaian rapatan dan regangan merambat sepanjang pegas. Rapatan
merupakan daerah di mana kumparan pegas saling mendekat, sedangkan
regangan merupakan daerah di mana kumparan pegas saling menjahui.
Gelombang longitudinal terdiri dari pola rapatan dan regangan. Panjang
gelombang adalah jarak antara rapatan yang berurutan atau regangan yang
berurutan. Yang dimaksudkan di sini adalah jarak dari dua titik yang
sama dan berurutan pada rapatan atau regangan. Salah satu contoh
gelombang logitudinal adalah gelombang suara di udara. Udara sebagai
medium perambatan gelombang suara, merapat dan meregang sepanjang arah
rambat gelombang udara. Berbeda dengan gelombang air atau gelombang
tali, gelombang bunyi tidak bisa kita lihat menggunakan mata.
Gelombang
air bukan sepenuhnya gelombang transversal atau gelombang
longitudinal. Gelombang air merupakan gabungan antara gelombang
transversal dan gelombang longitudinal.
Jika kita memukul batu di dalam air,
kita akan mendengar suara pukulan tersebut. Demikian juga, ikan yang
berenang di dalam kolam yang jernih, kita tentu akan beranggapan
ikan-ikan tersebut tidak bersuara. Akan tetapi, jika kita menyelam ke
dalam air, kita akan mendengar suara kibasan ekor dan sirip ikan
tersebut. Hal ini membuktikan bahwa bunyi dapat merambat di dalam zat
cair. Dengan bantuan alat seismograf, para ahli gempa dapat mendeteksi
getaran gempa bumi. Getaran lebih kuat jika jaraknya lebih dekat pada
sumber getar. Dari contoh-contoh tersebut, kita dapat menyimpulkan
bahwa bunyi yang terdengar bergantung pada jarak antara sumber bunyi
dan pendengar. Jarak yang ditempuh bunyi tiap satuan waktu disebut cepat
rambat bunyi (v). dan keterangan lainnya : frekuensi (f) adalah jumlah
osilasi yang dilakukan titik-titik pada medium selama satu sekon;
panjang gelombang adalah jarak antara dua pusat rapatan atau dua pusat
renggangan yang berdekatan. Secara matematis, hal itu dituliskan sebagai
berikut:
dengan :
v = cepat rambat gelombang bunyi (m/s)
v = cepat rambat gelombang bunyi (m/s)
s = jarak yang ditempuh (m)
t = waktu tempuh (s)
f = frekuensi gelombang (Hz)
λ = panjang gelombang (m)
λ = panjang gelombang (m)
Contoh soal :
Pada sebuah gelombang longitudinal memiliki panjang gelombang 2 m, bila frekuensi gelombang itu adalah 300 Hz, berapakah cepat rambat gelombang tersebut ?
diketahui: λ= 2 m
f = 300 Hz
ditanyakan : v =?
penyelesaian :
V= λ f
= 2 m . 300 Hz
= 600 m/s
Jadi, cepat rambat gelombang tersebut adalah 600 m/s
LONGITUDINAL WAVE
Waves
are vibrations that propagate in a medium or without medium of
propagation is not accompanied by parts of the medium itself.
Longitudinal waves are waves of vibration direction parallel to the direction of propagation. A series of density and strain propagates along the spring. Density is an area where the coil spring toward each other, while the strain is an area where the coil spring avoid each other. Longitudinal wave consists of patterns of density and strain. Wavelength is the distance between successive density or strain sequence. What is meant here is the distance of two points and the same sequence on the density or strain. One example logitudinal waves are sound waves in air. Air as a medium of propagation of sound waves, close together and stretched along the direction of propagation of the air. Unlike the water waves or waves of string, sound waves can not we see the use of the eye.
Not fully water waves transverse waves or longitudinal waves. Water waves are a combination of transverse waves and longitudinal waves.
If we hit a rock in the water, we'll hear the hit. Likewise, fish that swim in the pool crystal clear, we will certainly assume the fish is muted. However, if we dive into the water, we'll hear the flick of the tail and fin fish. This proves that the sound can propagate in liquids. With the aid of a seismograph, earthquake experts can detect earthquake vibrations. Vibration is stronger if the distance is closer to the source of vibration. From these examples, we can conclude that the sound is heard depends on the distance between sound source and listener. The distance traveled per unit of time is called the sound of rapid propagation of sound (v). and other details: frequency (f) is the number of oscillations made points on medium for one second; wavelength is the distance between two centers renggangan density or two adjacent centers. Mathematically, it is written as follows:
Longitudinal waves are waves of vibration direction parallel to the direction of propagation. A series of density and strain propagates along the spring. Density is an area where the coil spring toward each other, while the strain is an area where the coil spring avoid each other. Longitudinal wave consists of patterns of density and strain. Wavelength is the distance between successive density or strain sequence. What is meant here is the distance of two points and the same sequence on the density or strain. One example logitudinal waves are sound waves in air. Air as a medium of propagation of sound waves, close together and stretched along the direction of propagation of the air. Unlike the water waves or waves of string, sound waves can not we see the use of the eye.
Not fully water waves transverse waves or longitudinal waves. Water waves are a combination of transverse waves and longitudinal waves.
If we hit a rock in the water, we'll hear the hit. Likewise, fish that swim in the pool crystal clear, we will certainly assume the fish is muted. However, if we dive into the water, we'll hear the flick of the tail and fin fish. This proves that the sound can propagate in liquids. With the aid of a seismograph, earthquake experts can detect earthquake vibrations. Vibration is stronger if the distance is closer to the source of vibration. From these examples, we can conclude that the sound is heard depends on the distance between sound source and listener. The distance traveled per unit of time is called the sound of rapid propagation of sound (v). and other details: frequency (f) is the number of oscillations made points on medium for one second; wavelength is the distance between two centers renggangan density or two adjacent centers. Mathematically, it is written as follows:
v = rapid propagation of sound (m/s)
s = distance traveled (m)
t = time (s)
f = frequency (Hz)
λ = wavelength (m)
Example problems:
In a longitudinal wave has a wavelength of 2 m, when the wave frequency is 300 Hz, what is the rapid propagation of these waves?
unknown: λ = 2 m
f = 300 Hz
asked: v =?
completion: V = λ f
= 2 m. 300 Hz
= 600 m / s
so, rapid propagation of these is 600 m / s
