Skating on thin ice
Pressure – you feel it at school, your teacher feels it during class (yes, a room full of little scientists can be stressful for some teachers), and your dad feels pressure when Mom asks him for the tenth time to take out the trash. Here’s an interesting experiment that demonstrates a different kind of pressure – the forces of scientific pressure and how it can affect other objects.
- Place the corked bottle on a table. It helps if the bottle has a small neck.
- Balance an ice cube on the cork.
- Cut off a 12 inch section of wire.
- Tie two hammers or other heavy objects to both ends of the wire.
- Balance the wire across the middle of the ice cube.
How can the wire cut right through the ice cube without breaking it into two pieces? The pressure of the wire causes the ice to melt beneath it. The wire sinks easily through the melted ice, while the ice above the wire, which is no longer subjected to pressure, refreezes. This scientific principle also applies to ice skating. The pressure that your skates exert on ice causes a layer of water to form under the blades, creating a slick and slippery surface for sliding. It also explains one of the contributing factors to the slush that forms on heavily traveled roads after a ice or snow storm.
Supplies: Wire (bare), Corked bottle, Ice cube