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Transcript of Engineering Mechanics Friction. Friction: Layout Types of Friction Characteristics of Dry Friction...

• Engineering Mechanics

Friction

• Friction: Layout Types of Friction Characteristics of Dry Friction Coulombs Friction Model Friction Angle Simple Application: Wedge characteristics [,krkt'ristiks] n. characteristic

coulomb ['ku:lm] n.

wedge [wed] n.

• Types of Friction Dry Friction When the unlubricated surfaces of two solids are in contact under a condition of sliding or tendency to slide Fluid Friction When adjacent layers in a fluid are moving at different velocities Internal Friction - When solid materials are subjected to cyclical loading lubricate ['lubrikeit] vi.

• Characteristics of Dry FrictionFt: Friction Force N: Normal Force

impend [m'pend] vi.

coefficient [,kui'fint] n. []

• Friction: Example I A block of mass m is resting on an inclined plane. The coefficient of friction between the block and the plane is =0.25. Determine the maximum value of the inclining angle . Note: Inclining the plane may be used to estimate the coefficient of friction incline [in'klain] vi. value ['vlju:] n.

• Friction Force- Direction - MagnitudeCoordinate System- Standard- Rotated

• Friction: Example II Determine the range of values of force P applied so that the block of mass m will neither slide down or move up the inclined plane. Assume that the coefficient of friction between the block and the plane is =0.25 and the inclining angle of the plane is =45 .

• Friction: Example II Friction Force: Direction ?

• Friction: Example II

• Friction: Example III A square block of mass m resting on the horizontal surface is subjected to a horizontal force P. The coefficient of friction between the block and the plane is . Prove that equilibrium is broken by sliding if 0.5. square [skw] adj.