Friction Two solid objects sliding against each other. Drag The backwards drag of a solid object moving forward through a fluid. Two main causes
Cause of Friction • The hills and valleys of 2 objects acting upon each other.
Causes Cont. • Friction varies with the weight, normal force, pull, and force of friction on an object. • Objects are considered to be in equilibrium if the weight and normal force are = in size and opposite in directions.
Wet Friction Adding lubricants to reduce the frictional forces between parts. Examples Rolling Friction Adding rolling parts to an object to reduce frictional forces between parts. Examples Ways of Reducing Friction Oil, grease, water, etc. wheels, ball bearings, etc.
How lubricants work • Separates surfaces • Places friction on lubricant Picture here
How rolling friction works • Surfaces don’t scrape together as much • Frictional Force is always less than sliding friction. Picture here
Static Initial force used to start moving an object. Kinetic Force used to keep an object in motion 2 Modes of Friction Static > Kinetic
Drag • Produced by a fluid moving over a solid object. • Fluids can be a liquid or a gas • Acts just like a lubricant in its movement • Causes turbulence on the solid object • Increases in a linear pattern to a point • picture
Ways of Reducing Drag • Streamlining • Creating a more aerodynamic solid object to reduce turbulence • picture