B Ultrasonic wave and regular sound wave

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The speed of sound in gases is influenced by temperature and is described by the formula v = √(γP/ρ), where γ is the specific heat ratio. This formula applies to all sound waves, including ultrasonic waves, as they are not fundamentally different in speed from normal sound waves. The distinction between normal and ultrasonic sound is based on frequency, not speed. In ideal gases, the speed of sound remains consistent across frequencies, with only minor variations in real gases. Therefore, the teacher's assertion about different formulas for normal and ultrasonic sound speed lacks context and is incorrect.
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Does the speed of ultrasonic waves differ from the normal sound wave speed?
my teacher said that for normal sound wave speed v= √(γP/ρ)and for ultrasonic sound speed v= √(P/ρ) is he wrong?
 
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In air, water, or in solids?
All low-amplitude sound waves propagate at the same speed, independent of frequency.

In a gas, the speed of sound is dependent on temperature. Large amplitude sound waves, where the pressure wave can change the instantaneous air temperature, can be distorted, or become shock waves.
 
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I think gamma here is the ratio of the adiabatic to isothermal values for specific heat capacity. I will try to find out if there is a change as the frequency increases.
 
Hesh123 said:
is he wrong?
Yes, unless some context is missing. Ultrasound is just a name related to human hearing specifics. The formula without gamma was proposed by Newton and was latter corrected by Laplace by adding the gamma factor. The compression of air in a sound wave is better described as adiabatic rather than isothermal (as Newton assumed). The formula assumes an ideal gas, of course. In real gases there is a weak dependence of temperature and even weaker dependence on frequency.
 
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Hesh123 said:
Does the speed of ultrasonic waves differ from the normal sound wave speed?
my teacher said that for normal sound wave speed v= √(γP/ρ)and for ultrasonic sound speed v= √(P/ρ) is he wrong?
You can see from the reply by nasu #4 that your first formula applies at all frequencies.
 

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