State some important characteristics of wave motion.

Give four differences between transverse and longitudinal waves.

List in tabular form to distinguishing features between longitudinal waves and transverse waves. Give an example of each.

Distinguish between mechanical and electromagnetic waves.

What do you understand by the terms supersonic speed, shock waves and sonic boom?

Explain how a sonic boom is produced.

What is reverberation? How is reverberation controlled in an auditorium?

Two children are at opposite ends of an aluminium rod. One strikes the end of the rod with a stone. Find the ratio of times taken by the sound wave in air and in aluminium to reach the second child.

A stone is dropped from the top of a tower 500 m high into a pond of water at the base of the tower. When is the splash heard at the top? Given, g = 10 m s^–2 and speed of sound = 340 m s^–1.

A stone is dropped into a well, 44.1 metres deep. The sound of the splash is heard 3.13 seconds after the stone is dropped. Find the velocity of sound in air.

. A submarine emits a sonar pulse, which returns from an underwater cliff in 1.02 s. If the speed of sound in salt water is 1531 m/s, how far away is the cliff?

Let us consider some examples of motion : (a) Motion of a swing,(b) Motion of the hands of a watch,(c) Motion of the earth around the sun, All these motions repeat after some fixed interval of time. Such a motion is called periodic motion.The  motion of the swing is such that the swing moves to and from about its mean position Such a motion is called oscillatory or vibratory motion.
Answer the following questions based on the above information:
(a) Define periodic motion
(b) Define oscillatory motion
(c) Can a motion be periodic but not oscillatory?
(d) Motion of the earth is periodic but not oscillatory .Justify.

Waves needing a material medium to propagate are called mechanical or elastic waves.Waves not needing medium are called non-mechanical or electromagnetic waves.A mechanical wave generally has a velocity much smaller than that of a non-mechanic wave.Water waves,waves on a slinky,sound waves,etc are mechanical waves Radiowaves and light waves are non-mechanical waves.
Answer the following questions based on the above information:
(a) Classify waves on the basis of material medium.
(b) Which class of materials named by you does not require a material medium for propagation?
(c) Why are sound waves called mechanical waves?
(d) Suppose you and your friend are on the moon. Will you be able to hear any sound produced by your friend?

We hear a sound when a bell is rung If we touch the ringing bell, we can feel its vibrations.Thus,a source of sound in a sound in a state of vibration.The motion of vibrating source sets up sound in a state of vibration.These sound waves travel through air in the form of compressions and rarefactions producing sensation of hearing in our ears.
Answer the following questions based on the above information:
(a)What is sound?
(b) How is sound produced?
(c) What is the nature of sound waves in air?
(d) What is the separation between two successive compressions in a sound wave?

An average person can hear sounds in the frequency range 20 Hz-20 kHz .Sounds below 20 Hz are called infrasound and those above 20 kHz are called ultrasound The SONAR,a system of sound navigation and ranging ,employs ultrasonic waves and reflaction of sound for deducting and finding the distance of objects under water.
Answer the following questions based on the above information:
(a) What is the audible range of the average human ear?
(b) What is the range of frequency associated with infrasound?
(c) Wite the name of sound having  a frequency associated with infrasound?
(d) What for SONAR ,stands?
(e) Give an application of SONAR.

What is an echo? Give the conditions for the production of an echo.