Question

Please Help! If you send a sound wave of the same wavelength (_ = 2.00 m) through air, helium, and carbon dioxide, describe how the pitch of the sound will compare through each medium. Use calculations and your data to explain

Answer 1

Answer: The pitch would be maximum in Helium then air and then in carbon dioxide.

Explanation:

The speed of wave, frequency and wavelength are related as:

f = v/λ

Since the wavelength is constant in all the mediums, the frequency is directly proportional to the speed of the wave in the medium.

Pitch is dependent on frequency, greater the frequency, higher is the pitch.

Speed of wave in air at room temperature = 343 m/s

The frequency of wave in air ⇒ f =  343 m/s/2.0 m = 171.5/s

Speed of wave in Helium at room temperature = 1007 m/s

The frequency of wave in Helium⇒ f =  1007 m/s/2.0 m = 503.5/s

Speed of wave in carbon-dioxide at room temperature = 267 m/s

The frequency of wave in carbon-dioxide ⇒ f =  267 m/s/2.0 m = 133.5 /s

Thus, since the speed of sound is greatest in Helium, it has greatest frequency and hence highest pitch as compared to air. Pitch would be least in carbon-dioxide.

Answer 2

The density of air is about 1.29 kg/m^3, of helium .169 kg/m^3, and of carbon dioxide 1.98 kg/m^3. So the pitch would be highest for helium, in the middle for air, and lowest for CO2.