The ice at ice-skating rinks is made of brine (salt water) and is usually only 2.5cm thick. The ice is kept at around -5.50C and is made up of eight to ten layers of thin ice. Ice skating rinks are kept smooth by a special machine called a Zamboni, which was invented in 1940 by, you guessed it, Frank Zamboni. It cleans the skate-damaged ice by shooting down water onto it which flushes the grooves deep in the ice, loosening any dirt and debris, which are then collected and discarded. It then puts down a layer of heated water, which freezes and creates a smooth new surface. The Olympic luge event was introduced in 1964 at Innsbruck-Igis, Austria. The word "luge" is French for "racing sled." Lugers career down the course feet-first while lying on their backs. Luges are steered by the lugers exerting pressure on the sides of the car with their feet and shoulders. Several physical forces are demonstrated by a luge event. One is friction, the force that slows down moving objects when two surfaces rub together. Lugers attempt to reduce the force of friction by using the most slippery materials possible to construct the luge itself. But there are rules about what you can do to overcome friction. In 1968, the German Women's Olympic Team was disqualified for heating the runners on their sleds!

	Find out what happens when you take an ice cube out of the freezer.
	You will need:
	A freezer An ice cube tray Cling film A bowl of warm water Your fingers!
	Step One
	Fill the ice cube tray with water and put it in the freezer unit ice has fully formed.
	Step Two
	Take the ice cube tray out of the freezer and remove the ice cubes. Lay a piece of cling film in the freezer and place the ice cubes on top of it. Leave them in the freezer for a little while.
	Step Three
	Open the freezer and pick up one of the ice cubes with your fingers. You will see that the ice cube seems to stick to your fingers for a little while before coming loose.
	Step Four
	Warm your fingers up again by placing them in the bowl of warm water – be careful to avoid frostbite!
	Why does this happen?
	When your warm fingers touch the ice they melt its surface layer. Then heat from this newly melted ice flows into the middle of the ice cube, lowering the temperature of the outside layer enough to re-freeze it. So, what's actually happening is that your fingers melt a little bit of ice, and then the ice re-freezes that layer. After the ice is out of the freezer for a few seconds its surface is warmed by the warm air, causing it to melt and unstick it from your fingers. Sometimes this re-freezing effect can also freeze the surface of your fingers – this is called frostbite. Frostbite can also be caused by low air temperatures, and causes the fluids in the body tissues and cellular spaces freeze and crystallize. This can cause damage to the blood vessels and result in blood clotting and lack of oxygen to the affected area. It is better to prevent frostbite than to try to treat it, so keep safety in mind when travelling in cold weather, when taking part in winter sports and when out and about during the winter months.