Each one shows one or more science principles!
The magic glass with water and card stock cover.
Get a glass and one-third or half fill it with water. Lay a card stock cover
on top. Be sure that the cover extends past the glass. Now lay your hand on
the cover and turn everything upside down. Now remove your hand from the
cover. What happened?
Make your own Cartesian Diver.
Get a test tube from an aquarium supply or pet store . Find a clear, flexible
plastic bottle that the test tube will fit into and fill it with water. Now
you must put an amount of water into the test tube such that it will JUST
BARELY float when it is inverted and put into the bottle. It may take several
attempts to do this. Then put the cap on tight. What happens when you squeeze
the bottle? What happens when you release the pressure?
Pascal's principle of hydraulics: pressure inside a liquid is the same
everywhere. (Liquids are incompressible.)
Archimedes' principle of boats and submarines: a floating object displaces an
equal weight of water. A sinking object displaces less water than its weight.
Push the frog down so it stays stuck.
Now place it on a solid surface. What eventually happens? Why? What happens
to all that energy that you stored in the compressed spring by pushing it
down? Now put the frog on a sheet of construction paper held out level.
What happens now? Why the difference?
The colors are produced by the interference of light, a wave property, not by
colored pigments, like in paints. Iridescent bird feathers and some butterfly
wings produce colors the same way. The color seen on the bubble or feather is
the color (light wave) NOT cancelled out, and so it gets REFLECTED to your
eyes. An oil "slick" on water and the color seen on high-quality camera
lenses produce colors in a similar way.
A magnet affects a paper clip on the other side of a sheet of cardboard and
can move it "mysteriously" from underneath the paper.
Remove the paper clip and sprinkle iron filings on the paper to see the
magnetic field pattern. (Cut up an UNSOAPED steel wool pad with tin snips.)
A charged comb attracts water stream.
Adjust water from a sink faucet to be a very thin stream. Comb your hair and
hold the comb very close to the stream. What happens? Test other combs and
other people's hair. What do you notice? Which hair "works" best?
Use WASHABLE markers to make a line on a coffee-filter strip 1/2" x 3" and dip
the end into water. Rising water will separate colors of some "black" markers.
Test many different markers. Some inks may require solvents other than water,
such as rubbing alcohol, acetone, mineral spirits or lacquer thinner.
ACTION = REACTION
Blow up a balloon and release it. What happens? The air inside is accelerated
out the opening. So the balloon's reaction is the other direction. Stored
work (the compressed air inside) equals the flight distance of the balloon.
The simplest helicopter.
Move the right hand forward and the left hand back. The spinning blades
accelerate the air downward. What happens to the "helicopter".
IMAGES FORMED BY LENSES
Large and small magnifying glasses.
In a darkened room, form an image of a sunny window or lamp onto a sheet of
paper using a magnifying glass. What do you first notice about the image?
The image inside our eyes is like this, too! Why do things always appear
right-side-up to us?
Use a large magnifying glass to focus a tiny image of the bright sun onto thin
(gift-wrapping) paper and hold it motionless a while. What happens? Why?
Use two different magnification lenses and a clear light bulb to project the
filament image onto a wall. Which lens forms the biggest projected image?
Use a very strong magnifier to see: cloth, thread, a feather, insects, moth-
wing scales, fish scales, a butterfly's wing, pin point, salt crystals, razor
blade edge, onion skin, bee stinger, bread mold, hair, cotton, pond water
organisms, pollen, blood cells, torn-paper fibers, dollar bill engraving, etc.
A prism forms a spectrum of the white filament.
Observe the filament in a clear light bulb through a prism. Name the colors
in order. What color is always on the top of a rainbow? Where is the sun
when you are facing a rainbow?
Lay a laser pointer on a support so that the red dot hits a wall. Now put the
prism in the path of the laser beam. Where has the red dot moved to now?
A battery and coil becomes an electromagnet.
A coil of wire affects a compass when it carries a current. Change the battery
polarity to the coil and watch the compass needle. Why did that happen?
A moving magnet and a coil becomes a generator.
Connect a coil of wire to a sensitive meter (from a soil moisture meter) and
move the magnet over the coil. What happens when you move the magnet in one
direction? What happens when you move the magnet in the other direction? What
happens when you just hold the magnet against the coil? Why? What is the form
of the work that you put in? What is the form of the work that came out?
Speaker and sensitive meter.
Push the cone in and observe the meter needle. Reverse the clips on the
speaker terminals and push the cone in now. What do you observe.
A hose nozzle is a rocket motor!
Take the nozzle off a hose and turn the water on at the valve. Is there a
reaction force at the end of the hose? Now put a nozzle on the hose. Is there
a reaction force now? The nozzle accelerates the water one way. The hose
reaction is the other way.
The stuff to make match-head rockets.
A pin on the match forms the rocket nozzle.
Tear off a paper match. Lay a straight pin on the match so that the point is
on the match head. Tightly wrap a 3/4" x 3" strip of aluminum foil around the
match head and pin. Twist the front of the rocket foil into a point. Remove
the pin. Cut off excess foil at the point to reduce weight. Put the rocket
onto any launch pad.
The rocket ready to lift off.
Heat the match head with a barbecue lighter and watch what happens. Why did
it do that?
BERNOULLI'S PRINCIPLE (WING LIFT)
Small funnels and lightweight balls.
Hold a lightweight ball loosely inside a small funnel facing down and blow
into the funnel. Now release your finger from the ball. What happens to the
ball at first? What happens after you run out of breath? It may be necessary
to try different funnels and a ping-pong ball. On the right is a water-rocket
filling funnel and a small, hollow plastic ball from a toy set.
Balloon and hair dryer.
Set a hair dryer on low, aim it straight up and hold a 9" or 12" balloon about
a foot above the outlet. What happens? Move the air stream from side to side
under the balloon. What does the balloon do?
Spin a yo-yo down hard and let it "sleep" at the bottom. Now jerk the string.
What happens? What happens if you wait too long? In what form is the yo-yo's
stored energy? What is it changed into going up the string?
Spin a toy top and put it on a table or the floor. Or pull the string of a
gyroscope and set it on the plastic base. What happens?
Rotational inertia causes it to "precess" (the spin axis moves in a circle)
instead of tipping over. As long as it spins fast enough!
To show how a gyrocompass works.
It will be necessary to epoxy pivots to the gyroscope ring at these points.
Try to rotate the gyroscope horizontally and notice what the gyroscope does.
ELECTRICITY FROM CHEMICAL REACTION
Lemon juice, copper and zinc battery.
Put a copper wire and any galvanized (zinc) metal into lemon juice (acid)
and connect the wires to the terminals of the sensitive meter. What happens?
Reverse the connections. What happens now? Which metal creates the positive
(+) polarity? Stir baking soda into the acid and what happens? Why?
(Rinse the copper and zinc off thoroughly when done to avoid corrosion.)
IMPORTANT! The lemon battery produces much less power than a common battery.
So NEVER connect any household battery to the sensitive meter!
"STICK-SLIP" FRICTION (such as a bow on a violin string)
Make music the Ben Franklin way.
Wash and rinse your hands. Run a wet finger around the rim of a clean wine
glass. What happens?
Tuning fork and slide whistle.
Strike the tuning fork with a wooden spoon. (Never HIT the tuning fork on
anything!) What do you hear? Dip the vibrating arms into water. What do you
notice? Vibration creates sound.
Move the slide of the slide whistle while blowing in and what do you hear?
Human hearing is from 50 to 16,000 vibrations per second. The tuning fork
produces a single frequency of 320 cycles per second when hit properly,
musical note E. (If hit improperly, it produces two inharmonious tones.) The
slide whistle produces a wide range of frequencies if blown properly. Blown
improperly, it can produce inharmonious tones. "Practice, practice, practice."
ORGAN PIPE AND SLIDE WHISTLE
Blow across the top of a bottle. The sound is made by a "standing wave" inside
the bottle which makes your breath either go into or out of bottle at the
opening, due to either slight pressure or a slight vacuum from the standing
wave inside and thus reinforces the standing wave. The tone (note, frequency)
depends on the depth, just like the slide whistle. Add water to change the
depth inside the bottle. What happens to the tone as you add water?
The famous Drinking Bird.
Position the bird so that when tipped down, it's beak will dip into liquid in
a low glass. (To start the action, dampen the bird's head.) Observe all the
steps that happen next.
Evaporation of liquid on the head cools it. The vapor in the bottom bulb is
now warmer than the head(*). The red methylene chloride is pushed up the neck.
The bird now tips over and the head goes down into the liquid.
The alcohol in "adult beverages" (without ice) makes it go faster because
alcohol evaporates FASTER and so the head gets COLDER.
NOTE: It may be necessary to adjust the tipping point to make it work right.
To adjust it, slide the glass part up or down in the metal part.
Blow on the bird's wet head. What happens now? Why?
Hold the bird's lower half (glass bulb) in your hand. What happens now? Why?
(*) ALL thermodynamic engines work by producing a DIFFERENCE in temperatures.
The famous candle-powered Putt-Putt Boat.
The candle flame makes water percolate and spit water out the back. What
happens to the boat? Why? (Coffee percolators boil SMALL amounts of water
and small steam bubbles push hot water up and over the coffee grounds.)
BOILING WATER GRAPH
Graph the temperature of boiling water every minute from the time it is tap
water to when it's boiling, then continue for a few minutes afterward.
(Cooking thermometers must be used, not room thermometers.) Now look at your
graph. What has happened to the temperature?
Once water is boiling, always turn the heat down just enough to keep it
boiling ("simmer"). Leaving the burner on HIGH only wastes energy!
Look thru Polaroid brand sunglasses at an LCD timer or LCD calculator display
and rotate the sunglasses. What happens?
Immersion heater produces convection currents.
Put a coffee-cup heater into a glass coffee carafe and plug it in. Drip some
food coloring in while the water is heating and also float a few toothpicks on
the water above the heater. What happens?
Warm liquids and gases expand. After they expand, they are less dense. Cooler
fluid then PUSHES the warmer fluids up, but ONLY where gravity can act. So
convection cannot act on fluids while in orbit.
Stuff for making hydrogen balloons.
IMPORTANT: This must be done outside in good ventilation. Pool acid (muriatic,
hyrdrochloric) fumes are irritating if inhaled. And be aware that the bottle
gets hot when the chemical reaction begins.
Using an empty 3-liter beverage bottle, put 2 cups of water in it and then add
1 cup of pool acid (31.5%). Stretch a 10" to 12" (inflated-size) balloon over
the top of the #6 stopper, but only down about 1/8" because the stopper must
fit into the bottle without leaking. A #6 stopper can be obtained from a pet
supplies store, used for small-animal-cage watering.
Roll up a 12" square of aluminum foil to fit into the bottle and drop it in.
Wait a moment for the reaction to start and let the air be pushed out. After
the reaction bubbles briskly, push the stopper into the bottle and hold it in.
(The bottle will get hot, so touch only the stopper.) When the balloon is
blown up as much as it is going to be, pinch the balloon neck, take it off of
the stopper and tie a knot in it. Snip off any part of the rubber below the
knot to reduce weight. Tie a thread to your balloon.
You can ignite the hydrogen balloon with a long barbecue lighter while wearing
an oven mitt and goggles. The flame you'll get depends on the mix of air and