Q1 of 12 Page 137

Fill in the blanks and explain.

To discover a sunken ship or objects deep inside the sea, ....................... technology is used.

SONAR(Sound Navigation and Ranging)

Explanation: SONAR is used to determine the direction, distance and speed of an underwater object with the help of ultra sonic sound waves.


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1

Fill in the blanks and explain.

The velocity of sound in steel is …............ than the velocity of sand in water.

 1

Fill in the blanks and explain.

The incidence of ……… in daily life shows that the velocity of sound is less than the velocity of light

 2

Explain giving scientific reasons.

A. The roof of a movie theatre and a conference hall is curved.


B. The intensity of reverberation is higher in a closed and empty house.


C. We cannot hear the echo produced in a classroom

 3

Answer the following questions in your own words.

A. What is an echo? What factors are important to get a distinct echo?


B. Study the construction of the Golghumat at Vijapur and discuss the reasons for the multiple echoes produced there.


C. What should be the dimensions and the shape of classrooms so that no echo can be produced there?