subject: Sound Wave In Water [print this page] Wave motion is a kind of disturbance, which travels through a medium due to repeated vibrations of the particles of the medium about their man positions. In the wave motion, the particles of the medium do not move only the energy is transferred from one point to another. Here we discuss the sound waves in water.
Sound Wave in Water:
The sound waves are longitudinal in nature. The waves in which the individual particles of the medium oscillate along the direction of the propagation of the wave are called the longitudinal waves. In the case of the sound waves, which are travelling in water, the particles of the medium oscillate forward and backward in the direction of propagation of the wave. They cause compressions and rarefactions of small volume elements of the fluid. So that the speed of the sound wave in water can be determined by the following two factors.
(i) The volume elasticity or the bulk modulus (k) of water.
(ii) The density of water which determines the inertia of water.
So, we can say that the velocity of the sound wave in fluid or in water is given by
V = (k/'rho')1/2
Where, k is the bulk modulus of water and 'rho' be the density of water. From the above formula it is clearly seen that the speed of sound in water depends on the bulk modulus of water.
Uses of Sound Waves
(i) Geologists use the knowledge of sound waves to locate the oil reservoirs inside the earth surface.
(ii) Earthquakes can be detected by the waves travel through different kinds of rocks.
(iii) Sound waves are used in sonar, which can explore the sea bed and the entire sea.
(iv) Bats uses the sonar waves to detect the obstacles in the their path.
(v) Sound waves obey the rules of reflection so they produce echo. Echoes are used in medical fields.
(vi) Ultrasonic sound are used for examining the prenatal scanning.
(vii) Ultrasonic waves can be used to sterilize the delicate and costly instruments. In this process the instrument is suspended in the liquid and the ultrasonic waves pass through the liquid, which makes the liquid particles in the high frequency vibrations so that the surface of the instrument cleans.
(viii) Ultrasonic waves are used to detect the flaws and cracks in the metal sheets.
(ix) Sound waves are used to remove the congestion in lungs. There is a simple medical instrument called lung flute, which break up mucus in the chest cavity.
(x) Sound waves escaping from the Suns interior surface create lot of hot gases, which powers the chromospheres.
(xi) Ultrasonic waves are used in the diagnostic sonography, in which we can detect the body structures and the internal organs of the human body. We can detect the tumors by use of the ultrasonic waves.
Example for the Sound Wave in Water:
At the pressure of 105 Newton per squared metre, the volume strain of water is 5 10-5. Calculate the speed of sound in water. Density of water is 103 kilogram per cubic metre.
Solution:
Here, Pressure = 105 Newton per squared metre, Volume strain of water = 5 10-5, Density of water = 1000 kilogram per cubic metre, speed of sound (v) = ?
Bulk modulus of water = Pressure / volume strain of water
Bulk modulus = 105 / 5 10-5 = 2 109 Newton per squared metre
