to the image on the next slide.
a circle is IT and should shut his/her eyes or be blindfolded.
Test it!
and softer sounds.
Can the person who is IT point to where the sound is coming from?
still tell where soft sounds
are coming from?
cover up one ear with his/her hand
or use an ear plug to block the sound.
Your brain uses this information to figure out the location of the sound.
When you block the sound to one ear, this becomes more difficult to do.
because you have TWO ears.
Is sound a liquid or a gas? NO!
Is sound any form of matter? NO!
it's time for a 2 minute REVIEW -- of a KEY IDEA!
or metal cake pan
(optional)
To visualize what sound waves look like,
begin by making waves in water.
on the side of
the casserole dish
or rectangular cake pan.
the results,
shine a
bright light
from above.
on a flat surface.
Fill the casserole dish
about half full with water.
answer.
The waves bounce off the sides in almost straight lines.
Did they collide in the center?
travel in waves.
longitudinal waves,
you will need a slinky.
Stretch it out. DON’T PULL TOO HARD.
Either anchor it at one end or
have a friend hold at one end.
of the slinky and then release them.
Watch as the COMPRESSION
travels down the slinky.
COMPRESSION
is followed by
the spreading apart
of the springs.
as it moves down the slinky?
each individual coil on the slinky travels very little.
first to the right a little,
then backward to the left
toward its original position.
each spring moves from left to right and back again.
the motion of each spring
are along the SAME direction, left to right.
THIS IS MAKES IT A LONGITUDINAL WAVE!
THROUGH the gas particles from left to right.
The gas (air) molecules, like the slinky coils, move very little.
AND the molecules move forward to the right
and back again.
Even though sound waves
can travel very far,
the particles themselves only move a small distance.
or propagates down the line
in the animation.
each stick man only stands up and sits down.
through particles of air.
The compression waves are moving from left to right.
Notice that it moves only a small distance:
back and forth, back and forth, from left to right, and back.
a solid, a liquid, a gas or even a plasma!
right next to the Sun, a plasma,
WHAT WOULD IT SOUND LIKE
in a physical medium.
longitudinal wave
the same speed in all materials
on the surface of the Moon and WHY
require a medium
Sound waves require particles.
