# The Naked Scientists Forum

### Author Topic: What is the physics of curling?  (Read 3390 times)

#### versaith

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##### What is the physics of curling?
« on: 08/03/2015 20:33:10 »
I'll start off by saying, I am not any sort of scientist at all, my education is finance regrettably. Some people are fans of the NFL or NBA, I just happen to be a science fan. I also play Canada's second most popular sport at its top level. Outside of Canada you've probably never heard of curling. The problem is as follows....

Curling is played on a sheet of ice with 16 polished granite stones. The sheet of ice is spritzed by a sprinkler type thing leaving small frozen water droplets resting on the ice. It is called pebble. When a shot is thrown the stone is turned one way or the other. The sheet of ice is roughly 150 feet long and 15 wide. When conditions are best, while the rock travels the length of the sheet it actually will move or "curl" about 6 feet depending on how hard it is thrown. Two of the four players "brush" in front of the stone. Brushing in front melts the pebble, lessening the friction between the granite stone and the ice. If one brushes the stone from one end to the other the stone will travel further and its breaking point will be delayed.

The problem is that the pebble is going away too quickly. If more pebble is applied the speed changes drastically (which is an important part of the game) and makes it too difficult for the stone to reach the other end. They have thought about shortening the game, decreasing brush effectiveness but nobody has discussed changing the formulation of the pebble or perhaps changing both the formulation of the pebble combined with a different brush that will still impact the pebble differently. As it stands the pebble is broken down by the rocks traveling up and down the sheet, players brushing, players walking and whenever any body part touches the ice.
After it's all said and done pushing the stone down the ice needs to remain at a consistent difficulty level, brushing needs to impact the stone or two players will be eliminated from the game and it needs to last longer than purified H20. My thought was some sort of matching between pebble and brush. It would be nice if the only thing that impacting the stone was the brush and not heat or trampling from the players. There are plenty of YouTube videos of curling if you need to have a look and thanks!!!
« Last Edit: 13/03/2015 10:20:59 by chris »

#### David Cooper

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##### Re: 100 year problem
« Reply #1 on: 08/03/2015 21:36:01 »
Would it not be possible to spray just a tiny bit more pebble on after each stone is thrown? That way it would not suddenly slow down the whole track, but would maintain a constant speed. You really want some kind of machine that can analyse the ice with a laser and spray only those parts that need to be repaired, adding the right amount of droplets for each part of the track. This would repeatedly repair the whole surface except for under the any stones that are sitting on it. It would travel over the ice at walking speed. It needn't be done after each shot, of course - the pebble doesn't break up so badly as to need that, but it could do it after each end.

#### versaith

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##### Re: 100 year problem
« Reply #2 on: 08/03/2015 22:41:25 »
It's has been tried. We also tried a variation of that where we'd just pebble the houses very finely, but it just has far too much of an impact on speed. You'd be looking at about an eight foot difference that would slowly change throughout the end and make the speed different from player to player. If it were done in the early part of the game there would be areas that would get double pebbled in effect and be very slow. But you are 100% correct in that it would fix the problem, but the drawbacks would just outweigh the rewards.
Thanks very much for the reply though! I wasn't expecting anyone :)

#### alancalverd

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##### Re: 100 year problem
« Reply #3 on: 09/03/2015 00:09:35 »
I've been involved in sports such as rugby, cricket, golf, sailing and gliding, where the conditions vary significantly as the competition proceeds. The coaching spiel is always the same: "don't blame the weather, the pitch, the state of the ball, or anything else: the other guy is in exactly the same position."

#### Ophiolite

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##### Re: 100 year problem
« Reply #4 on: 09/03/2015 07:26:17 »
As a Scot I am familiar to a small extent with curling. It was my impression that the variability you are speaking of was desirable. In many (all) sports the ability to adjust to changing conditions is what separates the stars from the also-rans. What is the rationale for seeking to eliminate it in this instance?

#### versaith

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##### Re: 100 year problem
« Reply #5 on: 11/03/2015 00:33:57 »
It's really the same answer to both...variability is okay, but unpredictable variability brings a giant luck factor into play. In any sport you want a test of your ability not an unreadable test of luck.

#### versaith

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##### Re: 100 year problem
« Reply #6 on: 11/03/2015 00:39:27 »
"It's the same for both" is an argument used in many sports which is flawed. Bad conditions level the playing field. Same as golf. If the greens are absolute sh1t, then someone who is a great putter won't be able to showcase their skills. Those of us who have played a long time can tell bad ice SOLELY from line scores. You can diagnose a game looking at the teams playing and the numbers.

#### Ophiolite

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##### Re: 100 year problem
« Reply #7 on: 11/03/2015 07:40:52 »
Thank you for your replies. My ignorance of the subtleties of the game makes it difficult for me to buy in immediately to what you are saying. I shall have to resort to analogies to explain my thinking.

In golf one variability is wind speed. A gusting wind can be unpredictable. A skilled golfer will change club, percentage swing, target point, etc, in order to keep the ball low and thus minimise exposure to any gusts. Thus the top golfers can handle unpredictable and variable conditions.

What is the difference in curling? (I should note that I am confident you are correct. I am just trying to understand why you are correct. Your answers could create a new curling fan. :))

#### Colin2B

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##### Re: 100 year problem
« Reply #8 on: 11/03/2015 12:01:09 »
Outside of Canada you've probably never heard of curling.

We in the UK have heard of it, particualrly after the Olympic success of our women's team. Also the stones are quarried from an island Alisia Craig off the west coast of Scotland.

For those not familiar with the game and science, you might find this helpful in deciding on suggestions.

http://scottishcurlingicegroup.org/reports/Pebble.pdf

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##### Re: 100 year problem
« Reply #8 on: 11/03/2015 12:01:09 »