Sound Test - 70...

A metallic spoon falls on a metal plate making a huge sound and upon bouncing from the plate, it falls on to the pile of sand below it with no noise being heard. Sound is not heard on sand because

Match the following and select the correct answer from the codes given below.

A long spring whose one end is fixed is stretched from the other end and then left longitudinal waves of frequency $$500\ Hz$$ are produced. If the velocity of the wave is $$250\ m/s$$. Find the distance between two consecutive compressions and rarefaction.

Three different vibrating bodies produce three types of sounds X, Y, and Z.
Sounds X and Y cannot be heard by a man having a normal range of hearing but sound Z can be heard easily. 
The sound X is used to find faults and cracks in metals. The sound is similar to that which is produced during an earthquake before the main shock wave is generated.
Name one device which can produce sound like X.

Which one of the following material will reflect sound better?

A stone is dropped into a pond from the top of the tower of height $$h$$. If $$v$$ is the speed of sound in air, then the sound of splash will be heard at the top of the tower after a time:

An underwater sonar source operating at a frequency of $$60\ kHz$$ directs its beam towards the surface. If the velocity of sound in air is $$330\ m/s$$, the wavelength and frequency of waves in air are:

A person standing between a pair of tall and wide cliffs claps his hands. He hears the first two echoes at 2 sec and 3 sec respectively. If the speed of sound is 330 m/sec, then

Radio waves of speed $$3 \times 10^8 $$ m/s are reflected off the moon and received back on earth. The time elapsed between the sending of the signal and receiving it back at the earth station is 2.5 s. What is the distance of the moon from the earth(in km)?

An echo is heard because of the persistence of _____________