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STEM Students Sharing Science
S4School
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Busking for beginners
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Contents
Introduction ................................................................................................................................4
Acknowledgement.......................................................................................................................4
Further Resources........................................................................................................................5
List of Busking Demonstrations................................................................................................... 6
Anywhere busking........................................................................................................................7
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Straw Oboes (8)
Balloon Kebab (9)
Shrinking Coin (10)
Potato Straw (11)
Good Vibrations (12)
Loud lollies (13)
Music Box (14)
Magic Maltesers (15)
Levitating ping-pong balls (16)
Magic Jumping Bean (17)
Amazing Marshmallows (18)
Dropping a slinky (19)
Busking on a bench..............................................................................................................................20
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Alka-Seltzer Rocket (21)
Water-Proof Hanky (22)
Cartesian Diver (23)
Sour Grapes (24)
Quicksand Balti (25)
Stirring with spoons (27)
Do the Can Can (28)
Do floating beakers displace water? (29)
Cleaning coppers (30)
Spinning Plate (31)
Homemade hovercrafts (33)
Extra bounce (35)
Risk Assessment................................................................................................................................33
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Introduction
The simple demonstrations below have been chosen as they can be carried out successfully in a
variety of locations.
The key features of the demonstrations are:
•
Reliability and simplicity of operation.
•
Very little construction or pre-preparation is necessary.
•
Suitable for a range of audience ages and sizes, and venues
There are plenty more demonstrations available, and we would encourage you to develop your own
personalised demonstrations to highlight your particular area of interest.
Acknowledgement
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Further Resources
Those buskers interested in obtaining further information may find the following resources useful:
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The Little Book of Experiments by Planet Science www.planetscience.com/sciteach/index.html?page=/experiment/
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SciZmic – the Science Discovery Clubs network www.scizmic.net
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The Exploratorium www.exploratorium.edu
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British Interactive Group www.big.uk.com
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Professor Shakhashiri scifun.chem.wisc.edu
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Steve Spangler Science www.stevespanglerscience.com/experiments
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Planet Science’s Wired Science Magic Box
www.scienceyear.com/wired/index.html?page=/wired/magicbox
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The Surfing Scientist by the Australian Broadcasting Corporation
www.schoolscience.co.uk/teachers/chemclub/index.html
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Krampf Experiment of the Week www.krampf.com/news.html
Useful books:
Mad about Physics: John Wiley: ISBN 0-474-56961-5
Turning the world inside out: Princetown paperbacks: ISBN 0-691-02395-6
The Flying Circus of Physics: John Wiley: ISBN)-471-02984
Mad about Modern Physics: John Wiley: ISBN 0-474-44855-9
Why Toast lands jelly side down: Princetown paperbacks ISBN 0-691-02887-7
Riddles in your teacup: Institute of Physics: ISBN 0-7503-0275-5
Invitations to Science Inquiry: Science Inquiry Enterprises: ISBN 1-878106-21-X
Science Magic - fun guaranteed Sue Mc Grath ISBN 978-1-4259-7061-1
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List of Busking Demonstrations
Anywhere busking
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Straw Oboes (8)
Balloon Kebab (9)
Shrinking Coin (10)
Potato Straw (11)
Good Vibrations (12)
Loud lollies (13)
Music Box (14)
Magic Maltesers (15)
Levitating ping-pong balls (16)
Magic Jumping Bean (17)
Amazing Marshmallows (18)
Dropping a slinky (19)
Busking on a bench
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Alka-Seltzer Rocket (21)
Water-Proof Hanky (22)
Cartesian Diver (23)
Sour Grapes (24)
Quicksand Balti (25)
Stirring with spoons (27)
Do the Can Can (28)
Do floating beakers displace water? (29)
Cleaning coppers (30)
Spinning Plate (31)
Homemade hovercrafts (33)
Extra bounce (35)
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Anywhere busking
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1. Straw Oboes
A noisy, amusing demonstration of sound
What’s in the busking box?
•
•

Straws (need to be straight – cut off the bendy bits if there are any)
Scissors
Hole-puncher
Instructions
1. Flatten one end of the straw about 1-2cm from the end to the tip.
2. Make two cuts in the now flattened end of the straw, to form a triangular tip.
3. Put the triangular tip of the straw into your mouth and blow hard to make a. loud 'buzzing'
sound.
4. While blowing on the straw oboe, get a volunteer to cut the straw shorter, about 1cm at a
time. With each cut you will hear the pitch of the oboe sound go up.
It can take some practice to get the right sound – if it doesn't work straight away then slowly move
the straw in and out of your mouth whilst still blowing until you hear the sound.
Extension
Try doing the same thing with longer straws. Also you can use a hole-punch to make holes along the
length of the straw. Try playing the straw like a recorder.
Explanation
The triangular tip acts like the reed which can be found in most wind instruments e.g. oboe, clarinet.
Blowing on the reed causes the straw to vibrate. A standing wave pattern is created along the length
of the straw, which is heard as sound. The pitch of the note increases as you shorten the straw
because you shorten the wavelength of the standing wave pattern.
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2. Balloon kebab
This is properties of surfaces.
What’s in the busking in a box?
•
•
Balloons
Wooden kebab skewers
Instructions
1. Blow up the balloons (not full) and tie them off.
2. Make a 'balloon kebab' by inserting the wooden skewer all the way through the balloon
without popping it. Let a few of the audience have a try – they will usually try to insert the
skewer fairly slowly through the side, and the balloon will pop.
3. Show them how to make the balloon kebab. Start by lining up the skewer point with the
darker patch on the balloon, opposite the tie end. Gently push the skewer through using a
twisting motion. Once the skewer is through, push it gently through the balloon until the
point of the skewer is at the opposite end and insert the skewer tip gently through the soft
part of the balloon where the tie is using the twisting motion. You have made a balloon
kebab!
Explanation
A balloon is inflated by blowing air into it. Although most of the balloon stretches evenly there are
two points where the rubber is stretched less and therefore have the lowest surface tension. These
areas are at the tied section and the darker patch at the opposite side of the balloon. Because most
the balloon is under high tension, any attempt at pushing the skewer through causes the balloon to
pop. At the low tension sections (areas where the balloon is darker) it is possible to make a small
hole without breaking the surface of the balloon. This demo works best with round balloons that are
not blown up too much. Also make sure that the skewer ends are fairly sharp.
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3. Shrinking Coin
What’s in the busking box?
•
•
•
•
•
1x 1p coin
1x 2p coin
Piece of paper (approx 10cm x 10cm)
Pencil
Scissors
Instructions
1. Make a circle in the centre of a piece of paper by tracing around a 1p coin using the pencil.
2. Cut out the circle so that the piece of paper has a hole in the centre.
3. Show that the 1p coin slips easily through the hole.
4. Without ripping the paper or altering it in any way ask your audience to get the 2p coin
through the 1p-sized hole. Give out coins and paper and ask you audience to try for
themselves.
5. Show them how it can be done: Bend the piece of paper in half so that the bend is at the
bottom. Drop the 2p coin between the sides of the paper into the centre of the hole. Hold
the paper between finger and thumb near the bend, on either side of the coin. Slide your
fingers upwards around the coin. Allow the paper to buckle outwards perpendicular to the
coin. The coin should slip through the hole!
NB Don't use the same piece of paper too often because it will develop folds in it, which can cause
the coin to get stuck and this will help the audience would out the solution.
Explanation
Look at the corner of a room. The walls and floor are running in 3 directions showing 3D. The small
2D hole in a sheet of paper can be stretched in the third dimension to produce a slit that is large
enough to allow the larger coin through. This is all to do with non-Euclidean geometry!
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4. Potato Straw
What’s in the busking box?


A large potato
Straws
Instructions
1. Challenge your audience to see who can insert a straw the furthest into a potato. You could find a
number of volunteers, each with a straw and potato, and run the demo as a race timing them for
1min perhaps?
2. The volunteers will almost certainly twist the straws slowly into the potato.
When their straws are bent and not going in any further, show them how to do it:
 Hold the potato between thumb and fingers (note: do NOT have your hand behind the
potato!).
 Grasp the straw firmly about 2/3 of the way up (so you have plenty of straw to go into the
potato).
 Use a sharp thrusting movement to force the straw through.
Explanation
The sharp thrusting movement delivers a much larger instantaneous force (called a moment) rather
than the slow gradual twisting motion, thereby allowing the straw to get further.
The end of the straw has a very small surface area, so the force you impart is concentrated very
strongly.
If you tried to do the trick with a pencil roughly the same size as the straw you would find it much
more difficult – you would need to displace a much greater area of potato, which would require a
much greater force.
Notes
The straws need to be straight, with no defects. DON'T TRY TO RE-USE THE SAME STRAW.
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5. Good Vibrations
An amusing demonstration of how sound travels
What’s in the busking box?




Metal spoons
Metal coat hanger
Wooden spoon
String
Instructions
1. Tie the metal spoon to the centre of the string and wrap one end of the string about 5 times
around your index finger of your right hand.
2. Wrap the other end of the sting around the index finger of your left hand
3. Bend forward and allow the spoon to strike against different surfaces
Extension
Try doing the same thing again using a metal coat hanger or a wooden spoon
Explanation
This is about sound waves and how they travel through air and other materials. The spoon that is
attached to the string will vibrate when it is hit and the sound waves are transmitted to the
surrounding air molecules which carry the sound energy to your ear drums. The eardrums then feed
the movements into the ear known as the cochlea, where they are converted into electrical signals
that the brain can understand. High pitched sounds are transmitted to the air much more effectively
than lower frequencies which are why you hear the high ringing tones. The sting behaves as an ideal
conduit for the slower low pitched sound waves, which pass up the string into the fingers. By
sticking your fingers into your ears you make contact with the bones in your skull which carry the
low pitched sounds to you cochlea. This shows that solid materials are much more effective at
transmitting sound than a gas. The sting will transmit sound waves better than air. Now you hear the
low as well as the high frequencies
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6. Loud Lollies
What sound can you make?
What’s in the busking box?
•
•
•
•
•
Lolly sticks
Wide elastic bands
Narrow elastic bands
Straws
Scissors
Instructions
1. Wrap the wide elastic band lengthways around one of the sticks
2. Cut two short pieces of straw and place them in between the stick and the elastic band –
about 3cm form the end of each stick
3. Place the other lolly stick on top of the pieces of straw
4. Hold the ends of both the sticks together with the smaller elastic bands
5. Blow between the sticks
Extension
Bring the straws closer together and further away from each other
Explanation
Blowing through the lolly sticks makes the elastic band vibrate. This creates a sound.
If we move the straws closer to each other this shortens the section of the elastic band that can
vibrate and therefore raises the pitch of the sound produce
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7. Music Box
What’s in the busking box?
 Music box
 Small tray
Instructions
1. Hold the music box in the hand and turn the handle on the music box. Listen - What tune
can you hear?
2. Take the small tray and put the music box on the tray in one of the corners so that you can
still turn the handle. What happens to the sound?
Extension
Ask the audience how they could make the sound louder? Which musical instruments do you know
that uses this principle?
Explanation
If the music box is held in the hand and the handle turned a sound is produced as the air particles
are vibrated. The sound produced is barely audible at the back of the room. When the music box is
placed on a small tray and the handle is turned, the tray vibrates and in turn vibrates the
surrounding air particles. The result is an increase in the air particle vibrational motion and this in
turn increases the loudness or amplitude of the sound.
The larger the tray acts as a sounding board. The larger the sounding board, the louder the sound.
This is why the strings of a piano are attached to a sounding board and musical like violins and
guitars have sound boxes to amplify the sound of the strings.
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8. Magic Maltesers
Can you lift a Malteser off the table without touching it?
What’s in the busking box?
•
•
Plastic wine glasses
Maltesers
Instructions
1. Put a Malteser on a table with a glass on top of it. Move the glass quickly in a circular motion
and the Malteser will climb up the side of the glass.
2. Keep moving the glass and the n lift the glass up.
3. The Malteser should stay inside.
Explanation
The glass pushes inwards on the Malteser forcing it to move in a circle rather than in a straight line.
But due to the angle of the glass this means that it also pushes up on the Malteser as well supporting
its weight.
The Malteser Gravitron is a smaller version of what you can experience on the amusement park ride
of the same name. The inertia of the spinning Malteser is a "push" force. The glass supplies another
"push" force that keeps the marble moving in a "uniform circular motion." The force of the glass is
centripetal force, a force that makes a body follow a curved path. The combined forces of the
spinning marble and the glass create a relative force greater than gravity. This is a small scale
artificial gravity demonstration.
A real life application of this demonstration is how artificial gravity is created aboard a spacecraft. In
this instance, the rotating body is much larger (the spacecraft) and the spinning body (the astronaut)
needs to go around much more slowly to recreate the feeling of gravity. However, the same
phenomenon is present as the astronaut is able to stand upright against the outside of the
spacecraft.
Extension: Can you think of any other real-life scenarios where this is used?
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9. Levitating Ping-pong Balls
Why do aeroplanes stay in the air?
What’s in the busking box?
 Ping-pong ball
 Hair dryer with cold setting
 Straws
Instructions
1. Point the hair dryer so it is blowing a stream of air straight upwards. Alternatively use the
straw and blow a stream of air. Put the long part of the straw in your mouth and the short
shorter section should be pointing upwards. You will need to blow hard!
2. Hold the ping-pong ball in the stream of air and then let go.
3. The ping-pong ball bobs about in the air-stream without falling off.
4. Alter the angle of the air-stream – what happens to the ping-pong ball? Why does it not fly
away or fall to the floor?
5. The ping-pong ball will follow the air-stream even when it is tilted over 30 degrees.
Explanation
When air or a liquid flows over a curved surface it can stick to the surface and follow it so the flow
becomes curved. This means that when the ping-pong ball sits in centre of the air-stream, the flow
traps the ball by passing around it on all sides because the forces trying to move the ball to either
side are balanced. If the ball moves in any direction, the air sticking to its surface exerts a force in
the opposite direction pulling it back. (This is Newton’s Third Law which states that for every action
there is an equal and opposite reaction.) This causes the ping-pong ball to bop about in one place.
This phenomenon is the means by which aeroplanes generate lift. As the air passes over the surface
of an aeroplane wing it is deflected downwards by the curved surface. Because the air is push
downwards by the wing there is an equal and opposite force upwards providing lift and keeping the
plane air borne.
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10. Magic Jumping Beans
What’s in the busking box?
•
•
•
•
Magic Jumping Bean template
Marble
Glue
Scissors
Instructions
1. Before the demonstration prepare the Magic Jumping Bean as follows: cut out the template,
fold up the sides along the dotted line, placing the marble on the flat surface and glue the
outer strip to form a bean.
2. Place the Magic Jumping Bean on the surface and tilt the surface and watch what happens?
3. Ask the audience why the bean moves erratically?
Usual answers are that there is a magnet or it is powered by a battery...
Explanation
The Mexican jumping bean is momentum based demonstration. The erratic movement of these
paper boxes is actually simple physics. There is a marble inside the paper bean. When the marble
rolls internally to the bean's end, the bean flips with the momentum as the marble rolls forward
again this is repeated in a random fashion.
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11. Magic Marshmallows
What’s in the busking box?
 Food Saver
 Marshmallows
 Corn flour
Instructions
1. Roll the marshmallows gently between your hands in corn flour, otherwise they will just stick
to the sides of the foodsaver and make a big mess.
2. Insert the vacuum stopper into the neck of the foodsaver.
3. Tell the audience that the vacuum pump removes air from the plastic container and ask
them to carefully watch the marshmallows.
5 Pump the vacuum pump a few times – the marshmallows inside the plastic container begin
to expand.
4. Shake the container gently up and down to distribute the marshmallows throughout the
bottle, and then pump again.
5. Repeat until the marshmallows are no longer expanding. Discuss with your audience.
6. Tell your audience that you are going to let the air back into the bottle.
7. Remind them to watch the marshmallows closely as you do so.
8. Release the valve on the vacuum stopper – the marshmallows will rapidly shrink back to
their normal size.
Explanation
Marshmallows have small bubbles of air trapped inside them which are at atmospheric pressure.
When the air inside the container is sucked out, the volume of the container remains the same
although there is much less air inside – so the pressure is reduced. Therefore the air bubbles inside
the marshmallows are at a much higher pressure than the air surrounding the marshmallows, so
those bubbles push outwards, causing the marshmallows to expand. When air is let back into the
glass container, the surrounding pressure increases again, and the marshmallows deflate back to
their normal size.
Notes
Don't try to re-use the same marshmallows too much or they'll stretch and stop working properly.
Try using matchsticks to make marshmallow shapes – e.g. animals or a person – which the audience
can see grow and shrink as you decrease and increase the pressure.
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12. Dropping a slinky
What’s in the busking box?



Slinky springs
Stickers
Bluetack
Instructions
1. Hold the slinky spring vertically and drop
2. Look carefully at the lowest part of the spring and try and guess what will happen to the
spring there
Explanation
The lowest part of the spring remains stationary for a while and then begins to fall. The bottom coils
stay where they are whilst the upper coils catch up with them and the whole spring falls together.
During the motion the centre of mass falls with an acceleration of g (9.81ms-2)
Notes
Use different size slinkys to demonstrate this
A TV camera can be used to record the fall and looking at the result in slow motion will make this
easier to understand.
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Busking on a bench
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1. Alka-Seltzer Rocket
What’s in the busking box?



Empty film canister
Alka-Seltzer tablet
Water
Instructions
1. Place the Alka-Seltzer tablet in the film canister.
2. Add aprox.1cm of water.
3. Fit and tightly seal the lid on the canister.
4. Place the canister upside-down on a flat surface. Stand back!
Clean the canister lip and lid between demonstrations so that no pieces of Alka-Seltzer get stuck
between them, ruining the seal.
NB. It can be messy so is either most suited to locations that are easily or outside environments!
Explanation
Bubbles of carbon dioxide gas are given off when water is added to the Alka-Seltzer tablet. This gas is
contained within an enclosed space if the lid is tightly fitted. As more gas is given off the pressure
rises inside the canister until there is enough force to overcome the seal of the lid and to shoot the
canister into the air, forming the rocket.
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2. Water-Proof Hanky
This demonstration is based on surface tension and air pressure.
What’s in the busking box?
 Large glass
 Saucer or similar
 Water
 Cotton handkerchief
Instructions
1. Place the centre of the handkerchief over the glass, with the edges hanging over the outside
of the rim of the glass.
2. Fill the glass with water until the glass is roughly half full through the loose handkerchief.
Note the water easily passing through the handkerchief into the glass.
3. Now fill the glass to the brim with water and stretch the handkerchief taut over the top of
the glass. (For younger audiences you can say some 'magic words' that make the hanky
water proof.)
4. Place the saucer on the top of the glass and quickly tip it all upside down, being careful to
keep the handkerchief pulled tight.
5. Choose someone to from the audience and explain that you are going to hold the upsidedown glass and saucer above their head, making sure that the glass is vertical and the
handkerchief is tight. Remove the saucer. The water stays inside the glass.
NB. Some water may dribble out where the membrane attaches to the edge of the glass if the glass
isn't held vertically.
Explanation
Due to surface tension when the handkerchief is pulled tight, the water molecules can form a single
surface or membrane across the handkerchief. This provides a uniform surface for the air pressure
to act upon. The air surrounding us is exerting a force in all directions - air pressure. The air pressure
acting upon this membrane is sufficient to overcome gravity, and so the water stays in the glass.
When the handkerchief is loose, the water can pour through the gaps in the fabric. This
demonstration is based on surface tension and air pressure.
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3. Cartesian Diver
What’s in the busking box?
 Large plastic bottle (e.g.2L plastic lemonade bottle) with lid, filled with water
 Glass filled with water (for testing the ‘diver’)
 Unopened sachet of ketchup or brown sauce (or a 4 cm straw sealed each end with a small
piece of BluTack)
 Scissors
Instructions
1. Fill a glass with water.
2. Check that the unopened sachet of ketchup just floats in the glass of water. It should slowly
rise to the top of the water after you drop it in. If it floats too easily add one or two paper
clips to the sachet.
3. Fill a 2L plastic bottle with water.
4. Add an unopened sachet of ketchup. It should sit just at the surface of the water. If it is too
buoyant add one or two paperclips.
5. Make sure the bottle is full of water.
6. Screw the cap tightly on the bottle.
7. Squeeze the sides of the bottle (fairly firmly). The straw diver will sink through the water. Let
go of the bottle and the diver will float back up to the top. It may be easier to rest the bottle
on a flat surface and then use both hands to push the sides.
Explanation
The ‘diver’ contains an air bubble (nitrogen) sealed inside. When the sauce packet is placed in the
bottle it displaces an amount of water that weighs slightly more than it does and so bobs around on
the surface. When you squeeze the bottle pressure is applied to the water. Liquids are
incompressible so the pressure is transmitted to the air gas in the sachet. Gases can be compressed
so the sachets volume shrinks. The reduced volume displaces less water. This continues as the
bottle is squeezed more until the amount of water displaced weighs less than the sauce packet and
the sachet will sink. Releasing the pressure (by stopping squeezing the bottle) allows the air bubble
to expand back to its normal size, and so the ‘diver’ will float again.
24
4. Sour Grapes
What’s in the busking box?





3/4 pint fizzy drink
Nuts or raisons(a small handful)
Grapes
Pint glass
Spoon
Instructions
1. Fill glass 3/4 full with fizzy drink.
2. Add the nut or raisons.
3. Watch as the nuts or raisons gradually float up to the surface of the liquid, then fall back
down again.
Extension
What happens when you drop a peeled and unpeeled grape into the glass of freshly poured
lemonade?
Explanation
This effect relies on the gas contained within the fizzy drink. Bubbles form where there are rough
surfaces. At the bottom of the liquid, bubbles of carbon dioxide form on the nuts/raisons, and the
nut/raisons rise to the surface where the bubbles burst and the raison/nuts sink again.
The unpeeled grape goes up and down but the peeled grape sinks to the bottom and stays there.
There are not enough bubbles formed on the peeled smooth grape. The skin of the grape provides
the roughness required for the bubbles to form.
25
5. Quicksand Balti
Can you pick up a jar of rice without touching it?
What’s in the busking box?
•
•
•
Jam jar
Basmati rice
Knife
Instructions
1. Take a jam jar and fill it with rice
2. Push a knife of the same length as a jar and push it all the way into the rice.
3. Turn the knife around then remove it and reinsert it
4. If the level of the rice falls add some more rice
5. As it becomes more difficult to insert the knife you will be able to lift up the jar just using the
knife embedded in the rice.
Explanation
Particles organise themselves – first of all the grains take up random positions with large gaps
between them which makes it very easy to insert the knife because the rice can move and fill the
gaps.
As you repeat the process the rice grains begin to pack together in a much more organised fashion
and there is a lot less empty space which is why you many need to top up the rice as you do the
experiment
As you look at the jar you will see that most of the grains are lined up in the same way – in rows. In
this arrangement the rice takes up less space which increases the density of the rice so that it
becomes more difficult for the grains to move out of the way of the blade.
In the end it is only possible to insert the knife by breaking, cutting or distorting the grains which
require quite a large amount of force.
The grains will then push back on the knife with the same amount of force creating effective rice –
vice that grips the blade firmly with more force that it takes to lift the jar
Tips for success
Provide a variety of different tools to lift the jar and let your audience choose
Extension – how does this apply to quicksand?
26
Quicksand is composed of a mixture of sand and saltwater particles glued together with a small
amount of clay. It forms a structure very similar to a house of cards with large water filled spaces
between each of the sand particles
When you tread on quicksand the house of cards collapses and all the particles pack tightly together
around the trapped body part locking it in place. The force needed to pull you out is greater than the
force needed to lift a car because the sand is so heavy.4
Although you might get stuck – it is impossible to drown in quicksand because it is twice as dense as
you are so you will only sink waist high!
27
6. Stirring with spoons
The balance of wooden spoons
What’s in the busking box?
•
•
•
2 wooden spoons
Pivot
Scales
Introduction
1. A wooden spoon is balanced at its centre of mass and then cut in half at the balance point.
2. The two halves are weighed
3. Do the halves weigh the same?
Extension – male and female balancing
Balancing of the human body- ask a man first to stand facing a wall about three feet away from it
with their hands behind their backs.
Ask them to bend forwards so that their nose just touches the wall – women can do this without
overbalancing but men usually fall over!
Explanation
The head end is the heaviest – this is a simple explanation to the principle of moments.
The centre of mass of the head is closer to the pivot than the centre of mass of the handle then the
head must weigh more
Extension – Men have heavier upper bodies than women while women have relatively heavier hips
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7. Do the Can Can
Which tin will roll to the bottom first?
What’s in the busking box?
•
•
•
•
•
•
Tin of dog food
Tin of cat food
Tin of bake beans
Ramp
Scales
Tape measure
Instructions
1. Weigh the two tins and note down the mass in grams
2. Measure the two tins and note down their dimensions – both should be exactly the same
3. Hold them side by side at the top of the ramp and then let them go at the same time asking
the audience which one will get to the bottom of the slope first
Extension
Use a variety of different tins. Try two cans of fizzy drink but make sure that you shake one first.
Explanation
The can of dog food will get there first because the baked beans are moving within the other can
creating frictional forces which slow down the rate of rotation of the can and therefore make it roll
slower.
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8. Do floating beakers displace water?
Sink or swim - what will happen to the beaker?
What’s in the busking box?
•
•
Empty plastic beakers
Small plastic jug
Instructions
1.
2.
3.
4.
5.
6.
7.
Fill a beaker with water up to 1cm from the rim and float an empty beaker on top
Pour 1cm of water from the full beaker into the empty beaker and place on top
It will float but a little further down in the water due to the extra water it contains.
Fill the second beaker with water from the first leaving only 1cm in the first beaker
Will the second beaker float?
Will the water overflow in the first beaker?
How will the levels of water compare?
Extension
What will happen to the level of water in a lake when a bag is thrown from the rowing boat into the
lake?
Explanation
The water levels in both beakers will stay the same. The second beaker will still float and no water
will overflow. The water level will be the same in the first beaker as it was at the start.
This is a case of Archimedes Principle. In this case the weight of water displaced is equal to the
weight of the floating body. If the beakers themselves are almost weightless and have very little
volume then the water displaced is the same as the water in the floating beaker. Because the water
in the floating beaker is the water removed from the first beaker, then the water level in the first
beaker must return to the original value. It is also clear that the water level inside the floating beaker
will also be the level of the water outside.
Even a small amount of water in the floating beaker is sufficient to float the second because as this
beaker is lowered the water still surrounds it.
Extension explanation – it depends on whether the bag floats or sinks. In the boat and floating the
bag displaces its own weight of water but if it sinks it displaces its own volume of water, and hence
the box being denser than water the water level will fall.
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9. Cleaning coppers
Why are new coins bright and shiny but after a while they become dark and tarnished? Is it the fault
of oxygen or are we really dealing with dirty money?
What’s in the busking box?
 Copper coins
 Lemon juice
 White wine vinegar
 Small plastic cup
Instructions
1. Pour a little lemon juice or vinegar into a cup and place a coin against the inside of the
container so that half the coin remains above the level of the liquid.
2. Wait 5-10 mins and remove the coin and dry with a piece of kitchen paper
Extension
Have a go doing the same thing with cola or lemonade.
Copper is an acetate and if you evaporate all the vinegar away after cleaning the coins by placing a
saucer on a hot surface you will be left with some pretty green crystals
Explanation
This is the consequence of exposure to acid which can be used to clean unwanted oxides .The
technique can be used to sort out a rusty car.
The tarnish that forms on copper coins is caused by a metal reacting with oxygen in air to form
copper oxide. This is a black colour which is why the coin darkens as they age – the thickness of the
oxide layer increases. The oxide can be removed by adding an acid (e.g. white wine vinegar – acetic
acid or lemon juice citric acid) Acids release charged atoms known as ions H+ which can react with
the negatively charged oxygen in the copper oxide and turn into water. The copper associated with
the oxygen then dissolves leaving a clean copper surface
Tips for Success: Ensure that the copper coins are left in the solution for as long as possible
Offer to swap a clean 1p coin for a dirty 2p coin – this is the way to make millions!
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10. Spinning Plate
Can you make the plate spin?
What’s in the busking box?
• Spinning Plate
• Stick
Instructions
1. Attempt to spin the plate on the stick
2. Balance the plate on top of the stick.
3. With your spare hand, spread out your fingers so that you can grip the top of the plate a
little, and give it a spin by flicking your wrist.
4. Do not spin it too fast or it will fly off the stick. Don’t spin it too little as you won’t be able to
do many tricks.
The main problem that people have is lassoing the plate where the stick is staying in the same
position on the underside of the plate and therefore not speeding up and being flung around in a
circle. To stop this happening, get the plate started and then use your spare hand to grip your arm
and stop it moving completely! The wrist should be the only part of your arm that needs to move.
The wrist should speed up the plate till it looks horizontal, and then just stop your spinning, and the
plate will float to the middle.
Extension - ONE HANDED SPIN:
1. Place the stick on the rim of the plate (just like a jacket hanging from a hook). Slowly let your
plate circle the stick, so that the rest of the plate is not touching the stick.
2. Steadily increase your circular wrist motion, so that the plate speeds up.
3. Do not lasso the plate (the stick should go round the plate; it should not stay at the same
point on the plate).
4. Keep gradually increasing the speed and you will see the plate become horizontal. All you
need to do at this stage is to stop spinning your stick. The underside is sloped towards the
middle, so the stick will gravitate towards the middle of the plate.
Explanation
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Spinning plates have a large rim on the underside, and then it slopes towards the middle to allow
gravity to help you with your plate spinning! Spinning plates are among the cheapest toys to buy, so
there is no need to attempt with normal plates!
Plate spinning relies on the gyroscopic effect, in the same way a top stays upright while spinning.
Spinning plates are sometimes gimmicked, to help keep the plates on the poles. A gyroscope is a
device for measuring or maintaining orientation, based on the principles of angular momentum. In
essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any
orientation. Although this orientation does not remain fixed, it changes in response to an
external torque much less and in a different direction than it would without the large angular
momentum associated with the disk's high rate of spin and moment of inertia. Since external torque
is minimized by mounting the device in gimbals, its orientation remains nearly fixed, regardless of
any motion of the platform on which it is mounted.
SPIN TIME: A spinning plate once spun on the stick will maybe stay spinning for around 20-30
seconds. It is in this time that you can try a few tricks before having to stop to spin the plate again.
Tricks become very difficult when the plate is spinning slowly!
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11. Homemade hovercrafts
Find a good use for your old CD’s – get them moving
What’s in the busking box?
•
•
•
•
An old CD
Blue tack
Cap of a sports drinks bottle
Balloons
Instructions
1. Place the drinks cap over the hole in the CD and fix it in place with Blue Tack.
2. Blow up the balloon.
3. Make sure the sports cap is closed and pull the balloon over the cap – ensure that the air
does not leak out of the balloon
4. Place your hovercraft on the flat surface and open the sports cap
5. Give it a quick tap and watch the hovercraft go
Extension
Use different diameter disks and different surfaces –
Explanation
The air rushes out of the balloon and through the cap, lifting the CD up on a cushion of air .The air
reduces the friction between the CD and the surface that it’s on so that the hovercraft can travel a
long distance before stopping. Hovercrafts work by using air to lift a vehicle off of the ground. The
CD Hovercraft is no exception. As the balloon deflates, it is releasing air through the sports bottle
cap and beneath the CD. Because of the shape, smoothness, and weight distribution of the CD, the
releasing air creates a cushion of air between the CD and the surface. This cushion of air reduces the
friction between the CD and surface and allows your hovercraft to move more freely
To understand how hovercraft work, it is necessary to realize that the dynamics are more closely
related to aircraft than to boats or cars
http://www.discoverhover.org/abouthovercraft/works.htm
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Hovercraft floats on a cushion of air that has been forced under the craft by a fan. This causes the
craft to lift. The amount of lift can range from 15cm to 27cm depending on the size of the hovercraft.
The amount of total weight that a hovercraft can raise is equal to cushion pressure multiplied by the
area of the hovercraft. To make the craft function more efficiently, it is necessary to limit the
cushion air from escaping, so the air is contained by the use of what is called a hovercraft skirt.
Fashioned from fabric, which allows a deep cushion or clearance of obstacles, once "lifted" thrust
must be created to move the hovercraft forward. With many craft, this is generated by a separate
engine from the one used to create the lift. As the diagram above indicates, the fan-generated air
stream is split so that part of the air is directed under the hull for lift, while most of it is used for
thrust.
Now that the hovercraft has lift and thrust, it must be steered safely. This is achieved through the
use of a system of rudders behind the fan, controlled by handlebars at the front.
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12. Extra Bounce
What’s in the busking box?
•
Large ball that bounces (e.g. football or basketball)
•
Small ball that bounces (approx 10cm in diameter)
Instructions
1. Hold a large ball in front of you at shoulder height. Tell the audience that you are going to
drop the ball, and ask them to predict how high it will bounce.
2. Drop the ball.
3. Repeat the demonstration using a small ball.
4. Hold the small ball on top of the large ball at shoulder height and ask the audience what
they think will happen to each of the balls if they are dropped.
5. Drop the balls. The small ball will shoot off much higher than the sum of the original bounces
put together. Asking the audience to carefully watch the larger ball while you repeat the
demonstration. They will see that it hardly bounces.
In indoor spaces use a small ball that isn't too bouncy as it could potentially do damage. You
could try using a long ruler to help the audience judge how high the balls.
Explanation
Most of the momentum from BOTH balls is transferred to the small ball when both the balls are
dropped together. If the smaller ball receives all the kinetic energy and momentum from the larger
ball it will bounce much higher than the original larger ball because it is so much lighter. Add to that
the original energy and momentum in the smaller ball and you get a bounce that is much greater
than the sum of the two original bounces.
NB. This experiment is all about conservation of energy and momentum. The kinetic energy and the
momentum of any moving object depend on its mass.
This demo also demonstrates the effects of Chaos Note that a small changes in the initial conditions
such as how the two balls are held above one another can cause large differences in the end result.