Friction force stops or decreases the kinetic energy of a sliding object. However, in rolling objects, for example a wheel, friction force is the source of the translational motion. In this extended essay the order in magnitudes of the coefficients for sliding objects has been compared with the order in magnitudes of the coefficients of rolling objects. In other words do the materials with greater coefficient of sliding friction have a greater coefficient of rolling friction? In our daily life, we use rubber tires for our vehicles. However we may found a material that will be more efficient and safe in driving. udIn the experimental stage, a toy car is used and its wheels covered with different materials (rubber, sandpaper, aluminum, wood, leather). Toy car is released from an incline plane which is made of wood. In order to acquire accurate results, variables have been made constant. For each type of wheel, same brand of surface material is used. In each trial toy car is released from five different starting points which are on incline plane. Data obtained from the experiment is used for calculations for the coefficient of rolling friction between wood and material. udThe coefficient of rolling friction is calculated for each material with data obtained from the experiment. The results were precise and may contain some minor random errors. Calculated coefficients of rolling friction and the coefficient of sliding friction have been compared. This comparison showed that the order of magnitude between coefficient of friction for sliding objects and coefficient of friction for rolling objects are different. The ordering made between maximum values of literature values for sliding friction coefficients and average experimental values for rolling friction coefficient.udThis extended essay contaıns full details on the calculations, conclusion and evaluation of the experiment.
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