Explain how defects in a metal block can be defected using ultrasound?

How is ultrasound used for cleaning?

What is loudness of sound? What factors does it depend on?

What is reverberation? How can it be reduced?

A sound wave travels at a speed of 339 ms–1. If it’s wavelength is 1.5 cm, what is the frequency of the wave? Will it be audible?

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 ms–2 and speed of sound = 340 ms–1.