4.15 Reflection of Sound

When we hear the reflection of a sound wave that we produced, this is called

• sound amplification

• sound transmission

• a whisper

• an echo

Select all that apply. In order to hear an echo,

• the time between the original sound and the reflected sound must be greater than 0.1 s

• the time between the original sound and the reflected sound must be less than 0.1 s

• the distance between the original sound and the reflected sound must be greater than 17 m

• the distance between the original sound and the reflected sound must be less than 17 m

Select all the reasons why someone may not hear an echo when they yell loudly.

• The reflected sound is heard too soon, so the brain cannot distinguish between the original sound and the reflected sound.

• Sound is absorbed by non-sound-reflective materials in the environment.

• The sound intensity of the projected sound wave was too low.

• The person is standing in an empty, large building.

What does SONAR stand for?

• Science Navigation and Ranging

• Sound Navigation and Roaming

• Sound Navigation And Ranging

• Sound Negativity And Ranging

What is the purpose of SONAR?

• Using sound to determine the position of an object.

• Using sound to determine the mass of an object.

• Using sound to determine the color of an object.

• Using sound to determine the magnetic field of an object.

True or false? Submarines and ships are the only things in the world that use SONAR.

• True

• False

Mr. On is floating in his submarine and is worried about crashing into an underwater cliff. He sends out a SONAR pulse at 1500 m/s. The sound is reflected after 7 s. How far is Mr. On's submarine to the underwater cliff?

• 10, 500 m

• 5, 250 m

• 21,000 m

• 214 m