• Question: What do you think? What sport has the most friction involved during it :)

    Asked by 264sprg52 to Stephanie, LauraAnne, Katy, Helen, Emilia, Dan, Andrew on 7 Nov 2016.
    • Photo: Emilia McAllister-Jepps

      Emilia McAllister-Jepps answered on 7 Nov 2016:

      Hi, this is a really interesting question!

      There are two types of friction, static friction and kinetic friction. Kinetic friction is the friction force when the object is moving or sliding. Air resistance is also a type of friction.

      The force due to friction is generally independent of the contact area between the two surfaces. This means that even if you have two heavy objects of the same mass, where one is half as long and twice as high as the other one, they still experience the same frictional force when you drag them over the ground. This makes sense, because if the area of contact doubles, you may think that you should get twice as much friction. But when you double the length of an object, you halve the force on each square centimeter, because less weight is above it to push down. Note that this relationship breaks down when the surface area gets too small, since then the coefficient of friction increases because the object may begin to dig into the surface.

      Friction is a force that is apparent in every sport, for example; a boat will have friction force when moving through water, a runner will experience a level of friction between their body and the air, a cyclist will have friction acting on their tyres…

      In order to try and establish which sport has the most friction involved you could look at sports that have equipment specifically designed to reduce the effects of friction. A good example of this would be Swimming, there are now rules in swimming as to the kind of swimsuit that can be worn, as there are some suit designs that decrease the effects of friction, and therefore are advantageous in competition.

      If we use the premise that sports that involve air and water have the most friction, then that narrows the field down. Examples of these could be Swimming, Kayaking, Canoeing and Rowing.

      Given these examples, which one do you think could be most affected by friction?

    • Photo: LauraAnne Furlong

      LauraAnne Furlong answered on 8 Nov 2016:

      hmmm – friction can be seen in so many different places, there’s friction even between your foot and your shoe as you walk. The amount of friction is dependent on several things, the main one being a thing called the coefficient of friction, and this depends on the characteristics of the two materials that are in contact. Velcro for example has very high coefficient of friction!

      A rugby player playing in deep mud needs a high level of friction so they don’t slip and fall, so boots for this condition are big, rounded studs so they stick and sink into the ground and give grip. Hockey players play on astroturf which if you wear your normal runners on, you will slip very quickly as the grips on the bottom of your runners are very small. In contrast, the bottom of a hockey shoe have tough grips that stick out, which sink into the astroturf to provide grip so you can play and turn safely. The tyres on a road bike will have much less friction with the road than those of a mountain bike as they are narrower, and so they can move much more quickly on the road. Rock climbers need lots of friction between their hands and the rocks to make sure they don’t fall from heights, so they put chalk on them to reduce any sweating and improve grip.

      the frictional force is the coefficient of friction multiplied by the mass of the object in kilogrammes, so you get the most friction when you have a very heavy mass and a very high coefficient of friction. A quick search has shown that concrete on rubber has a very high cofficient (I would expect that rubber on rubber has even higher), so perhaps a very heavy person trying to ride a mountain bike on a concrete path has the highest friction?

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