Engineering Experiment on Friction
m = Ff – Rn
Rn = Normal reaction, weight force
Fn = Frictional force
But may also be worked out by dividing the force required in Kg by the weight of the object. Eg the force required to move a 25Kg object is 5Kg so to work out the coefficient of the object we would divide 5 by 25 to give a coefficient of 0.
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Because of this the surface area of the block is independent to that of the coefficient and is not needed when determining a value for friction.
The coefficient of wood against wood is 0.35 giving a relatively low value for friction whereas rubber against concrete is 0.8 meaning it would be hard to slide rubber on concrete. The coefficient can be greatly reduced if a lubricant of some sort is applied in between the surfaces as it forms a layer preventing the bumps on the surfaces rubbing together making it easier to slide the objects past each other.”