News / Edmonton

What makes a curling rock curl? This UAlberta scientist may have the answer

The University of Alberta professor emeritus Ed Lozowski claims to have finally found an answer to this most Canadian conundrum.

Skip Val Sweeting of Edmonton calls to teammates as a shot approaches the house during Olympic curling trials action Dec. 6 in Ottawa.

Adrian Wyld / The Canadian Press

Skip Val Sweeting of Edmonton calls to teammates as a shot approaches the house during Olympic curling trials action Dec. 6 in Ottawa.

Since beer was first chugged on a skating rink, people have longed to solve the mystery of what makes a curling rock curl.

Or, at least Ed Lozowski has.

The University of Alberta professor emeritus, working with Mark Shegelski at the University of Northern British Columbia, claims to have finally found an answer to this most Canadian conundrum.

“I think we’ve come up with a solution that explains why and how curling rocks curl,” said Lozowski, a former ice researcher in the U of A’s department of earth and atmospheric sciences.

“It will predict numbers, it will predict the amount of curl under certain conditions. So I’m quite happy with it – rather tickled, actually.”

Lozowski started researching ice years ago, after his experience as a speed skater made him curious about frozen water and what makes it slippery.

He came up with a numerical model to solve mathematical equations pertaining to ice friction and skates, and later worked out specific formulas for bobsledding and skeleton sledding.

While on sabbatical leave from the National Research Council, he started thinking about curling.

“I was kind of satisfied that I’d hit most of the sliding sports,” he said.

Norway team skip Ingvild Skaga watches the trajectory of a stone during the semifinal game between Norway and Canada at the World Mixed Curling Championship (WMCC) on Oct. 14, 2017.

Valentin Flauraud/Keystone via AP

Norway team skip Ingvild Skaga watches the trajectory of a stone during the semifinal game between Norway and Canada at the World Mixed Curling Championship (WMCC) on Oct. 14, 2017.

While his other equations only took about a year to sort out, curling had him scratching his head for nearly four years.

The first factor in determining how and where a rock will go is “pebbles” – tiny water droplets that are sprayed up into the air and then fall back down after freezing.

The rocks are not flat on the bottom, but sit on a circular “running band” that hits the pebbles as it slides, and pivot with each hit in the direction the rock is rotating.

The larger the diameter of the running band, the more the rock will curl.

“Every collision causes it to change direction ever so slightly,” Lozowski said.

“And the accumulation of all those encounters with pebbles and all the pivots eventually causes the rock to move sideways anywhere from about 3-5 feet.”

Sweeping lessens the amount of curl by heating ice, making it softer so the pebbles weaken and don’t stick to the rock as long.

There are other factors that go into predicting a curl distance, including the launch velocity, number of pebbles per square metre, shape and size of the pebbles, hardness of ice and the elastic co-efficient of the ice.

Lozowski is developing a technique to photograph the ice and automate the counting of pebbles to help icemakers with consistency.

As far as curlers, unfortunately, they won't have many practical uses for his equation.

“I wish I could give Canadian curlers an edge, but by golly, our Canadian curlers are already so good. They’re top of the world,” Lozowski said.

“They kind of already know what to do.”

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