Coefficient Of Friction

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Coefficient of Friction By Omar Ramadan Partners: Samuel Saarinen Brian Urbancic Feb 23, 2012 Abstract: The coefficient of friction is a number that determines how much force is required to move an object that is held back by friction. The goal of our experiment was to measure the static and kinetic sliding coefficient of friction between two surfaces by using a ramp and measuring its inclination. The premise is that when a solid object is placed on a ramp and the ramp is tilted upward, there is a point that the object starts to slide. That is the angle where the force of gravity is strong enough to overcome the kinetic and static friction. Once the angle, or the inclination, is known, we can then calculate the sliding coefficient of friction between the two surfaces. Experimental Description: In this experiment, to determine the coefficients of friction, both static and kinetic, our cart with an aluminum bottom was allowed to slide down an inclined plane. Several choices of covering for the inclined plane were given including aluminum, polyethylene, or left as bare wood. We raised the plane to an angle such that the cart would slightly start moving, then we measured the angle of the plane by using protractor and the sonic ranger to determine the acceleration of the cart (the calibration of sonic ranger – 0.012 percent error).This procedure was performed three times, each with a different inclined plane. Data and Analysis: The coefficient of static friction was derived in the following manner: Coefficient of static friction = (force of friction) / (normal force) Force of friction = horizontal component of gravity = m * g * sin α Force = vertical component of gravity = m * g * cos α Coefficient of static friction = m*g*sin α/ (m * g * cos α) = tan α Coefficient for kinetic friction = [g*m*sin α-(a/m)]/ [g*m* cos α] Where α is

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