surface texture and friction

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Introduction and Literature Review:

Friction is a force which opposes the movement of an object due to two surfaces being in contact with each other. Friction is affected by surface material (roughness), the surface area in contact and the mass of the object. The following investigation is to prove that friction will increase with increasing texture/’roughness’ of the surface material.

Surface texture and friction is dependent on the nature of the intermolecular forces present in the surfaces (R.Nave, n.d). When objects slide past each other intermolecular forces decrease , therfore decreasing friction. This is due to there being less molecules in contact with each other, the more contact there is the more friction there will be(Mann, 2013). All substances have different molecule sizes and so friction differs between different substances.

The surface texture is a factor in the maximum static friction and kinetic friction of an object. This is due to surface texture opposing the applied force; once the forces opposing motion are overcome you reach the maximum static friction (Mann, 2013).If the object is pulled with a consant force after this kinetic friction can be measure, this value will decrease over time (R.Nave, n.d.). The formula derived from the information is that maximum static friction from this is fs(max)=µsN and for kinetic friction it is fk=µkN .(Mann, 2013)

Many studies have been done on the effects of surface texture and its affect on friction.When 2 extremaly smooth objects slide past each other the friction between these objects is so great they are welded togethor . This is used in metal cutting to weld metals togethor without having to melt them first. (CHEN, Ping , 1988). By changing surface texture , you ...

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...ted and applied more/less pressure on the sandpaper which effects how many particles are in contact .

In conclusion when surface texture is increased the force needed to move the object at a constant speed is increased. This proves the hypothesis made earlier in the practical that as surface texture increases so will friction increase.

Bibliography
Chen, P., 1988. Study of cold welding caused by friction in metal cutting. Wear, 121(2), pp. 173-182.
Mann, M., 2013. Mind Action Series : Physical Science Textbook and Workbook Grade 11 NCAPS. 2 ed. Cape Town: All Copy Publisher.
R.Nave, n.d. Hyper Physics. [Online]
Available at: http://hyperphysics.phy-astr.gsu.edu/hbase/frict.html
[Accessed 14 May 2014].
Ulrika Pettersson, S. J., 2003. Influence of surface texture on boundary lubricated sliding contacts. Tribology International, 36(11), pp. 857-864.

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