(1) Give an example to prove that sound can travel in water.
(2) Write two characteristics of the sound.
(3) A sound wave has a frequency of 20 Hz and wavelength 20 cm. How long will it take to travel 1 km.
(4) Why megaphone is used to make announcement.
(5)How ultrasonic waves are useful in ‘echocardiology’?
(6) A ship sends out ultrasound that returns from the seabed and is detected after 2 s. If the speed of ultrasound through seawater is 1200 m/s, what is the distance of the seabed from the ship?
(7) Write the difference between the infrasound and ultrasound.
(8) A echo is heard in 2 s. What is the distance of the reflecting surface from the source, given that the speed of sound is 342 m/s.
(9) Write the name of three bones which amplified vibrations several times in the middle ear.
(10) What is the minimum time interval between the original sound and the reflected one to hear echo?