Do Spikes Increase Friction? Benefits of Wearing Spikes for Runners

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Homework Help Overview

The discussion revolves around the effects of wearing spikes on running performance, particularly focusing on friction and energy expenditure. Participants explore whether spikes increase friction and the implications for different types of runners, such as sprinters versus middle and long-distance runners.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants question the relationship between the use of spikes and friction, considering how spikes might allow runners to push against the ground more effectively. There are inquiries about the efficiency of spikes over longer distances and the energy costs associated with using them.

Discussion Status

The discussion is active, with participants offering insights into the mechanics of spikes and friction. Some suggest that while spikes may provide necessary grip for sprinters, they could be less efficient for distance runners due to the energy required to pull them out of the ground. There is no explicit consensus, but various interpretations of the energy dynamics are being explored.

Contextual Notes

Participants reference the coefficient of friction and the physical effort involved in using spikes, indicating that assumptions about efficiency and energy expenditure are under examination. The discussion also touches on the varying needs of different types of runners regarding grip and energy use.

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Does wearing spikes increase friction if so how?

Is the main benefit of wearing spikes because it allows the runner to push against the side of the hole it makes, therefore directing a portion of the normal force forwards, unlike normal running where friction pushes the runner forward?

Middle and long distance runners in track often don't wear shoes with spikes. This is because they aren't pushing hard enough that there is a risk of slipping https://kaitcphysicsoftrack.weebly....rip onto the,spike makes - no friction needed.

How does not pushing hard enough result in a risk of slipping? Or is this statement untrue and if so why?
 
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Because of the coefficient of friction, there is a maximum horizontal force through contact with the ground. This also depends on how hard you can push into the ground.

If you want more than the maximum you get from simple friction then you need spikes. Sprinters may need this at least for the high acceleration phase.

Ultimately, using spikes on a good track may be less efficient, which is not a problem for sprinting but is for longer distances.
 
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PeroK said:
Because of the coefficient of friction, there is a maximum horizontal force through contact with the ground. This also depends on how hard you can push into the ground.

If you want more than the maximum you get from simple friction then you need spikes. Sprinters may need this at least for the high acceleration phase.

Ultimately, using spikes on a good track may be less efficient, which is not a problem for sprinting but is for longer distances.

Why is it less efficient? It seems like getting spikes into the ground doesn't take anymore energy than running without spikes?
 
aspodkfpo said:
Why is it less efficient? It seems like getting spikes into the ground doesn't take anymore energy than running without spikes?
You might have to look at specific sports science to get the best answer to that. Spikes have to be pulled out of the track with every step. Over a distance race that small extra effort might make a small difference. If you take the extreme case of very long spikes, then clearly it would be an effort to move at all!
 
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PeroK said:
You might have to look at specific sports science to get the best answer to that. Spikes have to be pulled out of the track with every step. Over a distance race that small extra effort might make a small difference. If you take the extreme case of very long spikes, then clearly it would be an effort to move at all!
When being pulled out, friction is exerted by the side of the walls downwards, thereby resulting in more energy expended?
 
aspodkfpo said:
When being pulled out, friction is exerted by the side of the walls downwards, thereby resulting in more energy?
Yes, there is friction on the sides when you pull something out. If you stick a knife or spike into something it takes effort to extract it. For running spikes that must be a small extra effort, but may add up over thousands of strides. And, if you don't need the extra grip that the spikes give you, then it's wasted effort. If you are sprinting, then the extra effort over a few dozen or a hundred strides is negligible, but the extra grip may be invaluable in powering along.

That's the simplistic theory I can give you. Note that I've qualified everything I've said, as I'm no expert in the science of running shoes. If you want to know more, then I'm sure the Internet has plenty on the sports science of running spikes.
 
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aspodkfpo said:
When being pulled out, friction is exerted by the side of the walls downwards, thereby resulting in more energy expended?
Then you push them in, you are dissipating energy into kinetic friction. When you pull them out, you are dissipating energy into kinetic friction. It is a lose-lose situation.
 
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jbriggs444 said:
Then you push them in, you are dissipating energy into kinetic friction. When you pull them out, you are dissipating energy into kinetic friction. It is a lose-lose situation.
Yes, wrt the pushing in, in effect you are running uphill slightly, like running on soft ground.