Physics of Sound

Investigation 1: Dropping In

Part 3

Sound and Vibrations

PHYSICS OF SOUND

OBJECTIVES

I can identify a sound source.

I can identify a sound receiver.

I can describe, orally and in writing, what happens to vibrations when volume changes.

SOUND AND VIBRATIONS

We will be exploring sounds made by two different objects. Watch how to use each object appropriately. Long gong Tuning fork

Treat the instruments with care.

If you hit them too hard, they may break.

TUNING FORK AND LONG GONG

You will get time to get to know the instruments, then you will use them for an investigation. 5 minutes to explore Repackage instrument Switch with another group

GETTERs get materials.

STARTERs watch the clock and make sure everyone gets a turn.

SHARE OBSERVATIONS

Return all materials to the bags.

Think-Pair-ShareWhat did you hear?What were the properties of the sounds you heard?

What did you see when the two instruments made sounds?

DOOR FIDDLE

Guess what the teacher is making.

What do you see?

What do you hear?

How does the string feel when it is making its sound?

TONE GENERATOR

Watch the beans!

What do you see?

What do you hear?

How does the speaker feel when it is making its sound?

TONE GENERATOR

The quick back-and-forth movement of the string and speaker cone that you observed is called a VIBRATION.

Sometimes vibrations are so fast that they are easier to feel than they are to see.

Some vibrations feel like a tickle or a buzz.

Where have you felt vibrations? What did you hear when you felt the vibration?

INVESTIGATE

We will use the long gongs and tuning forks to do detailed investigations.

This time you should look for vibrations when the turning fork and the long gong are making their sounds.

STUDENT SHEETS

Open your yellow Physics of Sound packet to “The Tuning Fork” and “The Long Gong.”

Look at the headings. You will be expected to record information on these sheets while you investigate.

READ THE INSTRUCTIONS CAREFULLY. Underline key words!

MINIACTIVITIES

STARTERs read the instructions aloud to the group.

After that, GETTERs get the materials.

When you are done with one activity, have a teacher check your sheet. They will let you know if you can move on to the next activity.

THINK ABOUT

What causes sound?

What is vibrating when you hear the sounds?

T-P-SReturn materials.

THE SOURCE

Close your eyes. Be VERY quiet. Listen carefully to the sounds all around you for the next minute or so.

Raise your hand and identify a sound you heard.

Sound comes from a source. A sound source is where a vibration starts. Usually a sound source is a vibrating object, like a wire arch, a tuning fork, or a speaker cone.

THE RECEIVER

In order for a sound source to be heard, is must be detected (found) by a sound receiver. A sound receiver is something that responds to vibrations generated by a sound source.

Our ears are our sound receivers.

What other sound receivers can you think of?

VOLUME

Demonstration: work with volume dial on tone generator, keeping the pitch the same.

What is the sound source?What is the sound receiver?How is the sound changing?What happens to the vibrations when the sound is louder or softer?

VOLUME

Volume describes how loud a sound is.

STRONG vibrations make LOUD sounds.

Weak vibrations make soft sounds.

Volume is measured in decibels, named for Alexander Graham Bell, the inventor of the telephone.

VOLUME

Explore volume with the door fiddle, tone generator, tuning fork, and long gong.

Identify the sound sources and receivers.

How intense (strong or weak) is the vibration while the sound is being made?

OBJECTIVES

I can identify a sound source.

I can identify a sound receiver.

I can describe, orally and in writing, what happens to vibrations when volume changes.

REVIEW/REFLECT

What do vibrations have to do with sound?

What are some examples of sound sources?

What are some examples of sound receivers?

What happens to the vibrations when the volume changes?

SOUND

VIBRATION

SOURCE

RECEIVER

VOLUME