Why is ice so slippery?

Everything Water

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by Mya Kagan (whyzz writer) >> more about the author

Ice-skating is can be a really fun activity… strap on a pair of skates and you can glide across the smooth, hard surface of the ice! But when you step off the ice rink, have you ever noticed that your skates don’t glide so easily over other smooth, hard surfaces, like cement or tile?? That’s because other surfaces don’t have the same unique and awesome properties of water that make ice slippery and help facilitate activities like ice-skating!

Although we know a lot about the make-up and properties of water, the reason why ice is so slippery has remained a rather slippery question – scientists are still debating the reason behind this neat phenomenon!

One solution deals with friction, which is what happens when you rub one surface against another. Friction can create heat (think, for example, of the way your hands get warm when you rub them together), so some scientists think the friction of an ice-skate’s blade rubbing against the ice might cause a slight warming of the ice and the melting of the outermost layer, which leaves the ice slippery beneath you!

Another idea says that ice is just a slippery substance! Ice is made up of little units of water that are frozen together. Some scientists believe that ice has a slippery surface because the units of water on the outside have no layer above them to hold them in place, so even when still frozen and not yet melted, they move easily and create a slick, slippery surface!

For a long time, many answers about why ice was slippery pointed to pressure. This idea stated that ice was slippery beneath a pair of skates because of the pressure that the skates’ metal blades (carrying your weight on top of them) exerted on the ice caused it to melt faster, allowing you to glide across. Today, however, this theory is believed to be inaccurate; new calculations show that the pressure exerted by an ice-skater wouldn’t be enough to cause any significant melting.

Ice age!

Here's an icy-cold experiment you can try at home to learn a little bit more about ice!

Get two cups of water -- one cold, and one warm. Put them into the freezer at the same time and then come back after 10 minutes.

Which cup of water is closer to being ice? Has the water in one cup frozen faster than the water in the other cup?

Why do you think the two cups of water didn't freeze just as much as each other??