GREAT
EXPLORATIONS - Moving air | Forming
images | Reflecting light | Electricity
and magnetism | Spinning things | Making
sense | Changing colours | Making
sounds and waves | Moving to and fro
| Thinking about shapes
This is an old set of proven ideas, for reference. My latest designs are
far better!
Makings
sounds and waves
Voice
delay tube
TEXT:
Speak into one end of this long
tube.
Can you hear the sound of your voice come
out of the other end?
The tube runs right round the building and is
about 80 metres long. Sound travels through air at about 330 metres per
second. It is taking roughly a quarter of a second for your voice to reach
the other end of the tube.
A very successful design! Sectional, push-fit plastic tube has been used
so it is readily dismountable. There are hand grips and a step for small
children. The ends of the tube are positioned to allow you to hold your
ear beside one while speaking into the other.
Reflected
sound
(Sorry, no picture.)
Raise the handle, then pull it
down sharply to make a loud "crack".
Listen for the echo, as the sound bounces
back from the ceiling.
Try standing at the other side of the room while
your friend makes the "crack". Now do you notice a different
delay between hearing the sound and hearing its echo?
The sound is produced by two heavy leather straps slapping together.
The echo effect is subject to correct positioning of this exhibit in a
suitable building. Great Explorations had a domed roof with striking acoustic
properties.
Resonance
tubes
TEXT:
Put your ear close to each of these
tubes and listen.
Which tubes seem to produce the higher notes:
the longer ones or the shorter ones?
Sounds in the room are making the air inside
each tube vibrate up and down like a spring. Would a shorter spring vibrate
more quickly than a longer one? Have you ever heard sounds like this in
a large seashell or drinking cup?
Domino
effect
TEXT:
Stand up all the pieces of wood,
then push one over.
What is travelling along the row of 'dominoes'?
What do you think happens in a water wave? Does
the water flow along with the wave, or does each bit of water just move
to-and-fro in the same place?
The robustly hinged 'dominos' are made from ash and nicely finished.
They make a wonderful sound as they fall and there is a bell on the end,
rung by the last piece to go over.
Talking
robot
TEXT:
Speak into this robot's mouth.
Ask a friend to stand beside the other robot
and talk to each other through the tube.
Alternatively, you might be able to give somebody
a surprise as they walk past the other robot!
Tubular
bells
TEXT:
Gently knock the tubes.
Why do you think each tube stops ringing
if you touch it?
Touch a tube lightly with a piece of paper or
a fingertip while it is ringing. Can you feel it vibrating? Which tubes
make the higher notes: the longer ones or the shorter ones?
This is a good exhibit, but it did originally show one of my more stupid
design misjudgements! Kids banged the tubes together, making far too much
noise. The simple modification needed was to drill the lower end of each
tube and connect them with a nylon cord fastened at both sides in such
a way that they can't make contact with each other.
GREAT
EXPLORATIONS - Moving air | Forming
images | Reflecting light | Electricity
and magnetism | Spinning things | Making
sense | Changing colours | Making
sounds and waves | Moving to and fro
| Thinking about shapes
This is an old set of proven ideas, for reference. My latest designs are
far better!
|
