Sound can travel through a vacuum, a space with no air or matter in it.

Circle one:   True   False

What does sound always need in order to travel from one place to another?

• A medium, such as air, water, or a solid
• Bright light to guide it
• Nothing, sound can travel through empty space

Your ear rests against one side of a wooden door. A friend taps the other side softly. Which solid can carry the tapping vibrations to your ear?

• The empty space beside the door
• The wood making up the door
• The light reflecting off the door

A bell rings underwater and a listener is underwater nearby. Which liquid medium can carry the sound between them?

• Water around the bell
• Air above the water surface
• Wood beside the water

Why can you hear someone talking through a wall, even though you can't see them?

• Sound only travels through open doors
• The wall makes its own sound
• Sound vibrations travel through the solid wall

In a string telephone, what happens right after you speak into the cup?

• The other cup vibrates before your cup does
• Your cup vibrates in response to your voice
• The string vibrates before your cup does

Two astronauts are separated by a vacuum. Their radios are off, and no solid connects them. One taps their helmet. Why can the other not hear the tap?

• No medium spans the gap to carry sound
• The vacuum carries sound, but their helmets block it
• A quiet tap cannot make the first helmet vibrate

Priya makes a string telephone but leaves the string hanging loose, not pulled tight, between the two cups. What happens to the sound?

• It gets stronger because slack strings carry vibrations better
• It stays the same because the string's tightness has no effect
• It gets weaker because slack strings carry vibrations less well