Presentation on theme: "Static and Kinetic Friction"— Presentation transcript:
1 Static and Kinetic Friction Nerik Yakubov Robert Magee David Chen
2 Instructional Objectives Distinguish the Difference Between Static & Kinetic FrictionSolve Problems Involving Friction Effects
3 What is Friction?Force that acts oppose the relative motion of two surfacesHigh for dry and rough surfacesLow for smooth and wet surfaces
4 Free Body Diagram Normal Force FN Applied Force F Friction Force ff Gravity Force FgFg = mgFN = Fgff = F
5 Static FrictionThe Force of Static Friction keeps a stationary object at rest!FNFfsFg
6 Kinetic FrictionOnce the Force of Static Friction is overcome, the Force of Kinetic Friction is what slows down a moving object!MotionFNFfkFg
7 Types of Friction I better be safe Ump!! To initiate motion of the box the man must overcome the Force of Static FrictionUpon sliding, the baseball player will come to a complete stop due to the Force of Kinetic FrictionI better be safe Ump!!
8 Static & Kinetic Friction Coefficients MaterialCoefficient of Static Friction SCoefficient of Kinetic Friction SRubber on Glass2.0+2.0Rubber on Concrete1.00.8Steel on Steel0.740.57Wood on Wood0.25 – 0.50.2Metal on Metal0.150.06Ice on Ice0.10.03Synovial Joints in Humans0.010.003
12 Kinetic Friction Lab Procedure Line up the block with the motion detectorPush the block gently toward the motion detector so that it comes to a stop approximately 1 foot away from itFrom the velocity curve determine the deceleration of the blockCalculate the Force of Kinetic FrictionDetermine the coefficient of Kinetic FrictionWooden blockPush
13 Application AnalysisAn empty cart is being rolled across a warehouse floor. If the cart was filled, the force of kinetic friction between the cart and the floor wouldDecreaseIncreaseRemain the same
14 Application AnalysisSand is often placed on an icy road because the sand:Decreases the coefficient of friction between the tires of a car and the roadIncreases the coefficient of friction between the tires of a car and the roadDecrease the gravitational force on a carIncreases the normal force of a car on the road
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