Determination of Coefficient and Static Friction - Lab Report Example

There are two types of friction called kinetic and static friction. A static friction force (fs) acts on an object at rest while kinetic friction (fk) acts on moving objects.

          The maximum magnitude of kinetic friction force fk and maximum static force (fs, max) is directly proportional to the normal force N which is acting on the two surfaces:

From the experiment, it is clear that the static friction force for a block with one weight and a block with two weights is higher than the kinetic friction force for both masses. This is to enable the object to move at a constant velocity. The static friction force for blocks with one weight and two weights were 6.254 ± 0.7658 N and 3.773 ± 0.4060 N respectively. While the kinetic friction for the same masses was 2.472 ± 0.1193 N and 1.361± 0.09464 N. respectively. On the other hand, the coefficient of static friction for blocks with one weight and two weights was 0.6134 ±0.20297 and 0.5667± 0.1224 respectively.

While the coefficient of kinetic friction for the same masses was 0.22127± 0.1224 and 0.22400 ± 0.019076. Both the coefficient of static and kinetic friction was consistent with the values obtained by other groups. This result shows that the coefficient of static friction reduces as more weight is added to the object. The same scenario is also witnessed with the coefficient of kinetic friction. However, for a clear relationship to be obtained between the co-efficient of both static and kinetic friction more weights need to be added to the object to obtain a good relationship.

The obtained results showed that 70 % of the measurement lay in the (average ± one std. deviation). While 97.5 % of the friction force lay in the (average ± two std. deviation). Even though, the percentages of the measurements that lie (average ± one std. deviation) and (average ± two std. deviation) are slightly higher than 68 % and 95 % respectively.