Dice
Posts: 2
Joined: Sat Oct 30, 2010 2:43 pm
Occupation: student

### Traction of sports cleats

I am studying the effect of dragging different sports cleats on grass and dirt, to find out the amount of traction each have.
I still need more information on how to find the traction. I was also wondering if wearing the cleats would make it easier for finding the traction, rather than just dragging?
Please reply if you can help me with these concerns or you have any other information that you think would be useful for my research.

agm
Former Expert
Posts: 289
Joined: Mon May 05, 2008 10:34 am

### Re: Traction of sports cleats

Hi Dice,

I moved your topic to the physical sciences forum where more experts will see it.

Have you started your background investigation? One really important concept in understanding traction is friction. These Wikipedia articles should be good starting places, but you might want to look up some of the references cited and put some of the terms into a search engine as well:

http://en.wikipedia.org/wiki/Traction_%28engineering%29
http://en.wikipedia.org/wiki/Friction

Your intuition that it matters whether you're wearing the shoe or not is absolutely correct. The maximum frictional force between two surfaces (the force that would prevent the shoe from slipping sideways) depends on the 'normal force' pressing them together (your weight pressing the shoe into the ground). This is the same reason that it's harder to slide a couch across the floor if people are sitting on it. If you test the traction of different kinds of shoes, the normal force will probably be something you want as a constant or control variable:

http://www.sciencebuddies.com/science-f ... bles.shtml

These project descriptions have some ideas to get you started on thinking about how to test the traction/friction:

http://www.sciencebuddies.org/science-f ... p022.shtml
http://www.sciencebuddies.org/science-f ... p013.shtml
http://www.scire.com/sds/Pages/trctact.html (looks like this requires some specialized equipment, but the ideas might be helpful)

Amanda

Craig_Bridge
Former Expert
Posts: 1297
Joined: Mon Oct 16, 2006 11:47 am

### Re: Traction of sports cleats

When it comes to cleats or anything that is designed to tear a surface instead of sliding over it, the properties of the surface can dramatically affect your result.

For example, if you just layed some sod that hasn't had time for the roots to grow into the soil it is sitting on, the break away point could easily be the slipping of the sod on the ground instead of the cleat tearing the grass mat. Different grasses have different growth behaviors that also may affect the outcome. Cleat design 1 might behave better on blue grass than cleat design 2 which might outperform on St. Agustine better than cleat design 1.
-Craig

Dice
Posts: 2
Joined: Sat Oct 30, 2010 2:43 pm
Occupation: student

### Re: Traction of sports cleats

Thanks! This will really help me in my research.

Dice

robertreavis
Former Expert
Posts: 89
Joined: Wed Aug 31, 2005 6:58 pm

### Re: Traction of sports cleats

The shoe cleat to grass interface has an analog in the railroad industry too. Consider a moving train when the brakes are applied, the train then applies a horizontal force to the track in an effort to slow down. What keeps the track from sliding across the sufrace of the earth? It is the attachment of the rails to the ties, rail clips that keep the rails from sliding across the ties, and the ballast, which locks the ties to the ground.

The next time you have a chance to look at track made for freight trains, look at the bottom edge of the rails and look for clips that bear against the sides of the ties. There is usually one clip every second or third tie in both directions. Think of them as train cleats.

Bob