SCIENCE 5

Sound Energy

The blare of an alarm clock, the beep of a car horn, the quack of a duck, and the rumble of thunder during a storm are all ​ (a)   . Sound is energy in the form of ​ (b)   passing through matter. A vibration is a quick back-and-forth ​ (c)   . Sounds occur when objects vibrate. Sound travels through solids, liquids, and gases. Sound ​ (d)   through empty space, where there is no matter.

Pluck a guitar string, and the string starts to vibrate. The vibrating string passes energy to the air around it. The sound energy travels outward as sound waves. A sound wave is a ​ (e)   that moves sound energy through matter. When the waves reach your ears, the waves make your eardrum vibrate, and you hear the sound made by the guitar string.

How Sound Travels

As sound waves move through matter, they set ​ (a)   into motion. The moving particles form a ​ (b)   . Areas with groups of particles that are bunched together alternate with areas of particles that are farther apart. The areas where particles bunch together are called ​ (c)  

Sound waves travel at different ​ (d)   through matter. Sound waves travel quickly through most ​ (e)   and liquids. Sound waves tend to travel more slowly through gases.

Read the text and complete the sentences.

1. The moving ​ (a)   form a pattern.

2. ​ (b)   are the areas where particles bunch together.

3. Sound waves move ​ (c)   through most ​ (d)   and solids.

4. Through ​ (e)   , sound waves tend to travel more slowly.

Match the following.

Frequency and Wavelength

Waves can travel in different ​ (a)   . They can carry different types and amounts of energy. But all waves have certain ​ (b)   . Frequency and wavelength are two of these properties.

The ​ (c)   of a wave is the number of waves that pass a point in a certain amount of ​ (d)   . Frequency is often described as the number of complete cycles a wave makes in one second. A cycle is one vibration.

Wavelength is the ​ (e)   between a point on one wave and a similar point on the next wave.

Match the following

When vibrations from an object slow down, how are wavelength and frequency affected?

When vibrations slow down, ​ (a)   becomes ​ (b)   and ​ (c)   becomes ​ (d)   .

Match the following

1.​ (a)   is a measure of how strong a sound seems to human.

2.​ (b)   is the height of a wave measured from its midline.

3. ​ (c)   is how high or low a sound is.

4. If you change the frequency or ​ (d)   of a sound wave, you change its pitch.

5. If you change the amplitude, or ​ (e)   , of a sound wave, you change its volume.

You stand outside a room with doors and windows closed.

Why can you still hear sounds made in the room?

(a)