Chapter 12Lesson 2

Sound

Please Do Now!In the margin at the top of the

page, list as many things as you can think of that make sound.

Share with your partner.

A vibration is a back-and-forth motion that produces sound.

As the bell of an alarm clock vibrates, it causes nearby air

particles to move.

A wave that transfers sound through matter is a sound

wave.

Sound waves transfer energy from particle to particle and move away from a vibrating

object in all directions.

Sound waves travel through solids, liquids, and gases.

A sound that bounces off a surface is a reflected sound or an

echo.

Sound waves travel through different materials at different

speeds.

Sound travels slowest in a gas. It travels more quickly through

a liquid, and travels most quickly through a solid.

Dolphins use echoes to navigate and find prey.

You hear sound when sound waves in the air make tiny organs in your ears vibrate

Diagram DeterminationLook at the diagram on pg. 309 of your science book and read the caption. In the margin of

you paper, write what you think would happen if one of the parts

of the ear stopped working.

Share with your partner.

The distance from the top of one sound wave to the top of the

next wave is a wavelength. The number of wavelengths that pass a point in one second is

called frequency.

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The highness or lowness of a sound is its pitch.

Amplitude affects the volume, or loudness, of sound; it is

related to the amount of energy in a sound wave.

We use sound waves in a sonar device to detect objects under

water.

Sailors use sonar to measure how deep the water is.

Do you think there is sound in outer space? Why or why not?

Exit Question