Chapter 11 Sound Numerical Problems

Q. 11.1.   A normal conversation involves sound intensities of about 3.0 × 10^-6 W m^-2 . What is the decibel level for this intensity? What is the intensity of the sound for 100dB?

Q. 11.2. If at Anarkali Bazar Lahore, intensity level of sound is 80 dB, what will be the intensity of sound there?

Q. 11.3.  At a particular temperature, the speed of sound in air is 330 m s^-1 . If the wavelength of a note is 5 cm, calculate the frequency of the sound wave. Is this frequency in the audible range of the human ear?
Q. 11.4. A doctor counts 72 heartbeats in 1 min. Calculate the frequency and period of the heartbeats.
Q. 11.5. A marine survey ship sends a sound wave straight to the seabed. It receives an echo 1.5 s later. The speed of sound in seawater is 1500 m s^-1 . Find the depth of the sea at this position. 
Q. 11.6. A student clapped his hands near a cliff and heard the echo after 5 s. What is the distance of the cliff from the student if the speed of the sound is taken as 346 m s^-1 ?
Q. 11.7. A ship sends out ultrasound that returns from the seabed and is detected after 3.42 s. If the speed of ultrasound through seawater is 1531 m s^-1 , what is the distance of the seabed from the ship?
Q. 11.8. The highest frequency sound humans can hear is about 20,000 Hz. What is the o wavelength of sound in air at this frequency at a temperature of 20 ⁰C? What is the wavelength of the lowest sounds we can hear of about 20 Hz? Assume the speed of sound in air at 20 ⁰C is 343 m s^-1 .

Q.11.9. A sound wave has a frequency of 2 kHz and wavelength 35cm. How long will it take to travel 1.5 km?

Q. 11.1.   A normal conversation involves sound intensities of about 3.0 × 10^-6 W m^-2 . What is the decibel level for this intensity? What is the intensity of the sound for 100dB?

Q. 11.2. If at Anarkali Bazar Lahore, intensity level of sound is 80 dB, what will be the intensity of sound there?

Q. 11.3.  At a particular temperature, the speed of sound in air is 330 m s^-1 . If the wavelength of a note is 5 cm, calculate the frequency of the sound wave. Is this frequency in the audible range of the human ear?

Q. 11.4. A doctor counts 72 heartbeats in 1 min. Calculate the frequency and period of the heartbeats.

Q. 11.5. A marine survey ship sends a sound wave straight to the seabed. It receives an echo 1.5 s later. The speed of sound in seawater is 1500 m s^-1 . Find the depth of the sea at this position. 

Q. 11.6. A student clapped his hands near a cliff and heard the echo after 5 s. What is the distance of the cliff from the student if the speed of the sound is taken as 346 m s^-1 ?

Q. 11.7. A ship sends out ultrasound that returns from the seabed and is detected after 3.42 s. If the speed of ultrasound through seawater is 1531 m s^-1 , what is the distance of the seabed from the ship?

Q. 11.8. The highest frequency sound humans can hear is about 20,000 Hz. What is the o wavelength of sound in air at this frequency at a temperature of 20 ⁰C? What is the wavelength of the lowest sounds we can hear of about 20 Hz? Assume the speed of sound in air at 20 ⁰C is 343 m s^-1 .

Q.11.9. A sound wave has a frequency of 2 kHz and wavelength 35cm. How long will it take to travel 1.5 km?