Write the applications of reflection of sound waves.

Audible frequencies have a range of 20 Hz to 20 x 10³ Hz. Express 't' is range in terms of 
(i) period T
(ii) wavelength air at
(iii) angular frequency w (Given velocity of sound in O°C = 331 m/s)

A fruit dropped from the top of a tree of height 200 m high splashes into the water of a pond near the base of the tree. When is the splash heard at the top given that the speed of sound in air is 340 ms^-1.

For the travelling : harmonic wave y(x, t) = 2.0 cos 2π [St - 0.0060x + 0.27], where x and yare in cm and t in s.
Calculate the phase difference between oscillatory motion of two points separated by a distance of,
(a) 300 cm
(b) 0.75 m (c)\(\lambda\over 4\)

A transverse harmonic wave on a string is described by y(x, t) = 5.0 sin (48t + 0.0264x + ), where x and y are in cm and t in sec. The positive direction of x is from left to right.
(a) What are its amplitude and frequency?
(b) What is the least distance between two success in crests in the wave?