7 ms·

This seems similar to the Magnus effect: https://en.m.wikipedia.org/wiki/Magnus_effect https://en.m.wikipedia.org/wiki/Magnus_effect (Spinning a pen fast enou

by leot 9y ago

This seems similar to the Magnus effect: https://en.m.wikipedia.org/wiki/Magnus_effect https://en.m.wikipedia.org/wiki/Magnus_effect (Spinning a pen fast enough can turn it into a wing, causing it to behave strangely when tossed upward)

vhodges 9y ago
The faster the rock spins, the less it will curl. Ideal # of rotations is about 2.5 or so.
- Nomentatus 9y ago
  Water is complex; surface tension like effects can happen in thin films of it other than at the surface. At greater speeds, these are reduced so the Magnus effect is reduced.
  - deleted 9y ago
    [deleted]
  - randomdata 9y ago
    So what allows for directional sweeping to make the rock curl even more than it normally would on its own? And why does the same directional sweeping technique, except applied in reverse, cause the rock to curl less than it normally would on its own? And why does applying sweeping with both techniques at the same time counteract the directional movement?
    - Nomentatus 9y ago
      Roughening the surface by sweeping thins the film at many points. Your latter two points are more interesting; flow is unlikely, but directional "surface tension" effects (actually organized Van der Waals forces) are certainly possible, given that water is an asymmetrical molecule (which is why surface tension happens at all.)
      - randomdata 9y ago
        As a follow up, what causes negative curl (when the rock curls in the opposite direction of rotation)? Not something you are bound to see in professional level arenas, but not uncommon in clubs. In fact, what makes club ice seemingly impossible to make behave like arena ice? There is a serious amount of research by Canadian universities that has gone into trying to make club ice act like arena ice for training purposes and the best we have been able to do is "almost the same".
        jrs235 9y ago
        Shitty ice. To add: Curling on ice used for other purposes too leads to shitty ice. The ice needs to be flat and level. Zambonis do not lead to level ice. Dual purpose rinks likely also don't shave the ice to ensure level and flatness. Likewise, gouges in the ice from skates causes unpredictability and some might compensate by over pebbling prior to playing. Also poorly/sparsely pebbled I've can lead to unpredictableness.
        randomdata 9y ago
        That goes without saying, but what are the exact mechanics? To your edit: > Curling on ice used for other purposes too leads to shitty ice Certainly skating ice is a whole other beast to curl on, but I'm talking about club ice: Ice that is only used for curling.
        jrs235 9y ago
        The club I curl at is strictly dedicated curling ice and most curlers there take care and pride in the ice and work to keep it clean and in to condition. But we are also open to introducing people and bringing new curlers in. Sometimes people don't wear ideal clothing. They will wear clothes that is linty/fuzzy. Some lint or fuzz gets in the ice and a slow curled stone goes over a piece in the ice which causes a lot of friction b pulling the stone and causing it to start curling the opposite way. That's what I often see. Another thing that sometimes messed with the ice and can cause negative curl is outside conditions. The building isn't perfectly sealed and there are doors to the exterior 3 feet from the outer sheets. If it's above freezing the warm air seeping in can cause the ice near the doors to be frosty or wet (or even colder than normal and harder to melt from some friction if it's extremely cold outside). Depending on conditions. This can mess with the friction between the ice and stone regardless of spin direction.
- jrs235 9y ago
  A rock spinning too fast will melt more ice in front of the stones path reducing friction and lubing the ice in front and possibly pulling water over to the inside curl side leading it to fall forward more and catch less on the curl side. P.S. This is just my speculation, not from physics but from being a curler.
  - vhodges 9y ago
    Sure no problem, I curl myself :)
elif 9y ago
Except inverted. Left spin on a ball makes it go right by Magnus. Left curl makes a stone curl left. I curl and play pool, so I've come up with reasons for the difference in my head. The slower turning side creates more friction because it grabs the ice, the faster side glides over rather than grabbing. This is obvious when you intently watch as the curl picks up at the end of the shot. QED, dunno why a bunch of non-curlers wrote these articles they should just curl.
- claar 9y ago
  >The slower turning side creates more friction because it grabs the ice, the faster side glides over rather than grabbing. Don't both sides turn at the same speed?
  - BenjiWiebe 9y ago
    Not relative to the direction of travel over the ice.
- kazinator 9y ago
  > The slower turning side creates more friction because it grabs the ice, the faster side glides over rather than grabbing. For surfaces that do not melt to create a liquid film, this intuition is wrong. If any sliding is taking place, then static friction has been overcome, and kinetic friction is at play. Dry surface kinetic friction doesn't increase with speed: well, the coefficient doesn't but the actual force does! https://physics.stackexchange.com/questions/48534/does-kinetic-friction-increase-as-speed-increases https://physics.stackexchange.com/questions/48534/does-kinet...
- snowwrestler 9y ago
  Soccer balls also curl toward the spin. Kicking a ball to impart left spin will make the ball curl to the left in midair.
- xorxarle 9y ago
  An example of this could be walking on a slippery surface, your shoes grip until a threshhold is reached where you slip and increased speed seems to reduce the friction. I imagine it like tiny bumps that repel the surface of the shoe so that there is less net contact. Or is that the second hypothesis in the article? The relationship between speed and friction is discussed here, also: https://physics.stackexchange.com/questions/29561/does-friction-decrease-as-objects-move-faster-against-each-other https://physics.stackexchange.com/questions/29561/does-frict...

by leot 9y ago

vhodges 9y ago

The faster the rock spins, the less it will curl. Ideal # of rotations is about 2.5 or so.

Nomentatus 9y ago
Water is complex; surface tension like effects can happen in thin films of it other than at the surface. At greater speeds, these are reduced so the Magnus effect is reduced.
- deleted 9y ago
  [deleted]
- randomdata 9y ago
  So what allows for directional sweeping to make the rock curl even more than it normally would on its own? And why does the same directional sweeping technique, except applied in reverse, cause the rock to curl less than it normally would on its own? And why does applying sweeping with both techniques at the same time counteract the directional movement?
  - Nomentatus 9y ago
    Roughening the surface by sweeping thins the film at many points. Your latter two points are more interesting; flow is unlikely, but directional "surface tension" effects (actually organized Van der Waals forces) are certainly possible, given that water is an asymmetrical molecule (which is why surface tension happens at all.)
    - randomdata 9y ago
      As a follow up, what causes negative curl (when the rock curls in the opposite direction of rotation)? Not something you are bound to see in professional level arenas, but not uncommon in clubs. In fact, what makes club ice seemingly impossible to make behave like arena ice? There is a serious amount of research by Canadian universities that has gone into trying to make club ice act like arena ice for training purposes and the best we have been able to do is "almost the same".
      - jrs235 9y ago
        Shitty ice. To add: Curling on ice used for other purposes too leads to shitty ice. The ice needs to be flat and level. Zambonis do not lead to level ice. Dual purpose rinks likely also don't shave the ice to ensure level and flatness. Likewise, gouges in the ice from skates causes unpredictability and some might compensate by over pebbling prior to playing. Also poorly/sparsely pebbled I've can lead to unpredictableness.
        randomdata 9y ago
        That goes without saying, but what are the exact mechanics? To your edit: > Curling on ice used for other purposes too leads to shitty ice Certainly skating ice is a whole other beast to curl on, but I'm talking about club ice: Ice that is only used for curling.
        jrs235 9y ago
        The club I curl at is strictly dedicated curling ice and most curlers there take care and pride in the ice and work to keep it clean and in to condition. But we are also open to introducing people and bringing new curlers in. Sometimes people don't wear ideal clothing. They will wear clothes that is linty/fuzzy. Some lint or fuzz gets in the ice and a slow curled stone goes over a piece in the ice which causes a lot of friction b pulling the stone and causing it to start curling the opposite way. That's what I often see. Another thing that sometimes messed with the ice and can cause negative curl is outside conditions. The building isn't perfectly sealed and there are doors to the exterior 3 feet from the outer sheets. If it's above freezing the warm air seeping in can cause the ice near the doors to be frosty or wet (or even colder than normal and harder to melt from some friction if it's extremely cold outside). Depending on conditions. This can mess with the friction between the ice and stone regardless of spin direction.
jrs235 9y ago
A rock spinning too fast will melt more ice in front of the stones path reducing friction and lubing the ice in front and possibly pulling water over to the inside curl side leading it to fall forward more and catch less on the curl side. P.S. This is just my speculation, not from physics but from being a curler.
- vhodges 9y ago
  Sure no problem, I curl myself :)

elif 9y ago

Except inverted. Left spin on a ball makes it go right by Magnus. Left curl makes a stone curl left. I curl and play pool, so I've come up with reasons for the difference in my head. The slower turning side creates more friction because it grabs the ice, the faster side glides over rather than grabbing. This is obvious when you intently watch as the curl picks up at the end of the shot. QED, dunno why a bunch of non-curlers wrote these articles they should just curl.

claar 9y ago
>The slower turning side creates more friction because it grabs the ice, the faster side glides over rather than grabbing. Don't both sides turn at the same speed?
- BenjiWiebe 9y ago
  Not relative to the direction of travel over the ice.
kazinator 9y ago
> The slower turning side creates more friction because it grabs the ice, the faster side glides over rather than grabbing. For surfaces that do not melt to create a liquid film, this intuition is wrong. If any sliding is taking place, then static friction has been overcome, and kinetic friction is at play. Dry surface kinetic friction doesn't increase with speed: well, the coefficient doesn't but the actual force does! https://physics.stackexchange.com/questions/48534/does-kinetic-friction-increase-as-speed-increases https://physics.stackexchange.com/questions/48534/does-kinet...
snowwrestler 9y ago
Soccer balls also curl toward the spin. Kicking a ball to impart left spin will make the ball curl to the left in midair.
xorxarle 9y ago
An example of this could be walking on a slippery surface, your shoes grip until a threshhold is reached where you slip and increased speed seems to reduce the friction. I imagine it like tiny bumps that repel the surface of the shoe so that there is less net contact. Or is that the second hypothesis in the article? The relationship between speed and friction is discussed here, also: https://physics.stackexchange.com/questions/29561/does-friction-decrease-as-objects-move-faster-against-each-other https://physics.stackexchange.com/questions/29561/does-frict...