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Friction. Physics is a drag!. Friction. The force that resist motion Ff Measured in Newtons Acts parallel to the surface in contact Acts opposite to the direction of motion. Things you should know. Depends on the nature of the materials in contact.
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Friction Physics is a drag!
Friction • The force that resist motion • Ff • Measured in Newtons • Acts parallel to the surface in contact • Acts opposite to the direction of motion
Things you should know • Depends on the nature of the materials in contact. • Independent of speed or area of contact. • Proportional to the force pressing the surfaces together (same as FN) • 2 kinds • Static (stationary-force you must overcome to start moving) • Kinetic (between surfaces that are moving)
Coefficient of Friction • Symbol : µ • A value that represent the amount of friction between 2 surfaces (no units) • Calculated by taking Ff /FN • µs: coefficient of static friction • µk: coefficient of kinetic friction • To find Ff simply multiply µ by FN
FBD But how do you find Fg? Ff = µFN FN Fg = mg =m(9.80m/s2) F N = Fg but why? Fa Ff Fg