Curling is back. Yes, the simple-looking sport with the big stones and the brooms that the U.S. men’s team won gold in at Pyeongchang four years ago will captivate audiences once more in Beijing.
Turns out, though, it’s not as simple as it looks.
For one, the ice isn’t flat like a hockey rink. The stones' rotation goes completely against what physics generally tells us about how objects move when pushed. Oh, and those brooms are extremely important for producing pinpoint precision on the ice.
Yahoo Sports broke down curling on every level and you can experience it all in our immersive augmented reality pieces below.
What is curling?
For the uninitiated, curling is a sport in which two teams push stones down a sheet of ice toward "the house," or three concentric circles on the far end of the sheet. The closer you are to the center of the house, the more points your team scores.
Curlers can also sweep the ice as the stones travel to change the speed and direction of the stone to strategically place them around the house or hit other stones. If you have the closest stone, you get a point. If you have the closest and second closest you get two points, and so on. The team with the most points at the end of the match wins.
Check out the 3D model below to see what a curling stone looks like and where on the ice the teams are aiming to place them.
Make sure to unmute the experience by clicking the speaker icon in the upper right corner to be fully immersed. Don't miss the second carousel scene.
Why is curling ice bumpy?
Curling ice is carefully prepared with a process called "pebbling" to ensure the stones encounter as little friction as possible when gliding. This involves leveling the ice with a scraper, spraying water droplets that form pebbles and nipping those pebbles to create a unique, flat surface for the stones.
The pebbled ice helps the running band on the bottom of the stone come into contact with less ice, allowing the stone to travel further. You can see this process in the animation below, as well as a closer look at pebbled ice.
Click on the icon in the top right corner of the experience to enter full-screen mode. Remember to turn on the audio and don't miss the second carousel scene.
How does a curling stone curl?
Typically, objects move in the opposite direction they’re rotating. Try it out with a coffee mug on your table if you’re unsure. In a strange twist, though, curling stones move with their rotation.
There are a lot of different theories about why this happens. None seemed correct until Swiss professor Harald Nyberg’s 2013 paper explained that a curling stone's running band creates micro-scratches in the ice that affect the motion of the rest of the stone. The first part of the band leaves angled scratches on the top of the ice that the second part of the band runs into, causing the unique movement.
Below is a visualization of what way curling stones curl and why they move in that direction.
For the full experience, make sure to turn on the audio and zoom in to read the smaller text cards near the table. Don't miss the second carousel scene.
What are the brooms for?
This all leads to those brooms everyone keeps seeing. Curling is one of the only sports where the object can be influenced after it has been released. When someone sweeps the ice in front of a stone, it heats up the top layer of the ice to reduce friction and allow the stone to travel further. Sweeping can also alter the direction of the stone, which helps with aim.
The visualizations below show what sweeping does to the ice and illustrate several different directional sweeping techniques.
Make sure to click on each of the five carousel scenes to fully explore the experience.
A special thank you to Roger Rowlett, President Jim Rishel, and the Utica Curling Club for all of their help and support with this project.