# Class 9 Science|physics Extra questions for Sound

Assignments NCERT Solutions

Class 9 Science|physics Extra questions for Sound
Question 1.A person hears an echo from the top of a tower, 2.2 sec after the sound is produced. How far away is the tower from the person? Speed of the sound in air is 332m/s?
Question 2.How can multiple echoes of a single sound be produced? Explain?
Question 3.Define echo. Give its two application?
Question 4.When a sound is reflected from a distant object, an echo is produced and heard on a winter night. Will you hear the echo of the same sound on a summer day if the distance between reflecting surface and the source of sound remains the same? Justify your answer?
Question 5.Why are the walls and roof of an auditorium covered with sound absorbent materials?
Question 6.Define reverberation. What arrangements should be made in an auditorium to control excessive reverberation?
Question 7.Determine the minimum distance between the listener and reflector for an echo to be heard dintinctively of a sound propagating with a speed v m/s?
Question 8.Name the sound of the following frequencies:
a) 5Hz
b) 50Hz
c) 50000Hz
d) 50kHz

Question 9.Write full form of acronym SONAR. How the method of echo-ranging is used to detetmine the depth of the sea?
Question 10.Explain, how defects in a metal block can be detected using ultrasound?
Question 11.How bats can detect their prey?
Question 12.What is the frequency of a wave whose time period is 0.05s?
Question 13.A ship is stationary is at a distance of 2800m from the sea-bed. The ship sends an ultrasound signal to the sea-bed and its echo is heard after 4s. Find the speed of sound in water?
Question 14.A body is vibrating 6000times in one minute. If the velocity of sound in air is 360m/s, Find:
a) Frequency of the vibration in Hz
b) Wavelength of sound produced
Question 15.Explain with the help of a diagram the working of SONAR?
Question 16.A hospital uses an ultrasonic scanner to locate tumors in a tissue. What is the wavelength of ultrasound in a tissue in which the speed of ultrasound is 1.5km/sec2 ? The operating frequency of the scanner is 4.0 MHz?
Question 17.State any two characteristics of a wave motion?
Question 18.A ship sends out ultrasound that returns from the sea-bed and is detected after 3.22sec. If the speed of ultrasound in sea water is 1530m/s, calculate the distance of the sea-bed from the ship?
Question 19.How do the frequency and amplitudes affect musical sound?
Question 20.Explain how the human ear works?