AMAZING FACTS ABOUT WATER
• The great Ancient Greek mathematician Archimedes was fascinated by water, and once famously jumped out of his bath shouting ‘Eureka’, which is Greek for ‘that water was much colder than it looked’.
• It takes 150 litres of water to produce a pint of beer.
• In 1963, Tanzanian student Erasto Mpemba noticed that, in some circumstances, hot water freezes faster than cold water! The effect is now named after him, and scientists are still uncertain how best to explain this weird phenomenon.
• All of the water on Earth arrived in comets and asteroids between 4.5 billion and 3.8 billion years ago.
• Since life began, there has been the same amount of water on Earth, and so any glass of water may contain molecules that dinosaurs drank.
THE SEE-SAW
For this bet you need a battery, a ruler and two small cups of water. Place the battery on the table, the ruler on the battery, and balance the cups on either end of the ruler.
Now challenge your friend to make the see-saw move, but without touching the glasses or the ruler. To win the bet, simply dip your fingers into the water and the see-saw will move!
When you put your finger in the water, it increases the level of water in the cup. The deeper the water, the greater the water pressure at the bottom. There’s more water pressure acting on the bottom of the cup when you put your finger in it, and so the cup tilts the see-saw.
INSTANT HANDCUFFS
Borrow a banknote from a friend. Ask them to place their hands palm down on the table, and then explain that for the first part of this bet they need to balance two glasses of liquid on the backs of their fingers. Once they are in that position, you pick up the banknote and run!
The legendary Harry Houdini spent his entire life escaping from handcuffs, chains and prisons. However, according to several biographies of the great escapologist, there was one occasion when he struggled for the strangest of reasons. Whilst touring Scotland, Houdini was chained up in a jail cell and the door shut. He quickly freed himself from the chains and started to use concealed lock picks to open the cell door. Houdini struggled for over two hours but simply couldn’t open the door. Bathed in sweat and exhausted, he eventually fell against the door. The door swung open and Houdini discovered that it hadn’t been locked in the first place! All along, he had been trapped by his own mind.
ALL CHANGE
Draw an arrow on a piece of paper, and then challenge your friend to reverse the direction of the arrow without touching the paper.
To win the bet, just slide a glass of water in front of the paper and the arrow will appear to reverse direction.
THE UNDRINKABLE DRINK
Tell your friend you’re going to place their drink on the table in such a way that they won’t be able to drink it. To win the bet, place a thin piece of card over their drink and carefully turn the glass upside down (holding the card in place!).
Next, put the entire set-up on the table and then carefully slide away the card. Your friend won’t be able to get to their drink, and when they lift the glass the liquid will go everywhere!
This bet works best with a light, flexible, waterproof piece of card.
Press the card onto the glass as you turn it over.
Use a glass with a relatively large mouth and small base.
This bet is all to do with air pressure. Air pressure is pushing up on the card from below, and the weight of the water is pushing down on the card from above. The force from the air pressure counteracts the force from the water, and the card stays exactly where it is.
EVERY PENNY COUNTS
Fill a wine glass to the brim with water and ask your friend how many pennies you can drop into the glass before the liquid starts to run down the outside.
They will guess maybe one or two coins. In fact, amazingly, you can drop in at least ten pennies without spilling a drop.
The water molecules on the surface of the water cling together very strongly – this is known as surface tension. When you add the pennies the displaced water rises and forms a dome over the rim because the surface of the water stretches. However, add too many pennies and the surface tension won’t be strong enough, and the water will start to run down the side of the glass. If you add detergent to the water the surface tension will be much lower, and far fewer pennies can be placed in the glass before it starts to spill.
DOWN IN ONE
Place a straw in a bottle and tell your friend that you can move half of the liquid from the bottle into a glass, but without moving the bottle or sucking on the straw.
To win the bet, simply place your lips around the top of the bottle and blow. The air pressure will force the liquid through the straw and into the glass!
In 1888, Marvin Chester Stone, an American, invented the modern drinking straw. Stone wrapped paper around a pencil, slid the tube off the pencil, and applied glue to the side of the tube. These early straws were about eight inches long and very narrow, much like a modern-day cocktail straw. Stone’s simple invention has improved millions of lives because straws help prevent acidic soft drinks coming into direct contact with people’s teeth, and so significantly reduce tooth decay and cavities.
Unlike many nineteenth-century industrialists, Stone cared deeply about his workers. He provided them with a well-stocked library, a music room and a dance hall, and constructed tenement houses for Washington’s African American residents.
IN THE CAN
Bet your friend that you are able to balance an empty drink can on its rim.
When your friend accepts the bet, place about 100 millilitres of water in the can and you will find that you can balance it on its rim. In fact, if you give the can a gentle tap, it will roll around the table on its rim!
When you have a can of liquid, its centre of gravity is roughly in the middle of the liquid. As a result, a can containing lots of liquid has a relatively high centre of gravity. When you attempt to balance the can on its rim, the centre of gravity won’t be in line with where the rim touches the table, and the can will topple over. When you pour away some of the liquid, however, you lower the centre of gravity, and at some point the can’s centre of gravity will be directly above where the rim touches the table. Now the can will balance at a seemingly impossible angle.
A FANTASTIC FLOTATION
Fill a glass with water and challenge your friend to float a paper clip on top of the water. Every time they place a paper clip in the glass it will sink to the bottom.
To win the bet, bend one paper clip into an ‘L’ shape, and then balance another paper clip on the arm of the ‘L’.
Finally, carefully place the entire arrangement on the top of the water. Amazingly, the paper clip will float.
The bet works because the molecules on the top of the water are held strongly together by surface tension, forming a thin film. This film can support very light objects, provided that they don’t disturb the tension. If people use their hands to place the paper clips in the water, the oil on their fingers disturbs the tension. Use an L-shaped paper clip, however, and the tension remains intact.
And if you want to win the bet even when your friend knows how to put in the paper clips, secretly add a drop of liquid soap to the water. The soap will break up the surface tension, and the soapy water won’t support a paper clip no matter how carefully it’s placed in the glass!
THE DIVING BELL
Screw up a paper napkin and place it in the bottom of a glass. Make sure that the napkin is touching the sides of the glass so that it won’t fall out if the glass is turned upside down. Now tell your friend that you can put the glass completely under water, but without getting the napkin wet.
To win the bet, push the glass into a bowl of water mouth first. The air pressure will stop the water getting into the glass and the napkin will remain completely dry!
HALF FULL OR HALF EMPTY?
Fill a straight-sided glass three-quarters full of water. Then challenge your friend to pour some of it out until they are left with exactly half a glass of water.
To win the bet, pour the water until there’s a straight line between the rim and the base of the glass – then you have exactly half a glass of water.
