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Friction Friction and Newton’s Laws Static and Kinetic Friction Coefficient of Friction Practice. Exploring Frictional Forces. TeachWithFergy Preview File. If you decide to purchase and the lesson isn't exactly what you need or thought it was, I will refund you 100% via PayPal.
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Friction • Friction and Newton’s Laws • Static and Kinetic Friction • Coefficient of Friction • Practice Exploring Frictional Forces
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Friction • The analysis of friction is very important to practical situations since friction is present everywhere. • Friction is a good and bad thing. • Good when our tires meet the pavement • Bad when reducing efficiency and/or producing heat In slideshow mode,click the image and your video will start automatically
Friction • Friction always opposes motion (or Fnet) • Kinetic friction • Static friction • Air resistance
Friction and Newton’s Laws • Friction is simply a force included and accounted for in a FBD. • Applies to situations where: • Fnet = 0 • Fnet = ma
Static Friction • The magnitude of the force needed to start a stationary object moving is the maximum static friction, FSmax
Kinetic friction • Kinetic friction acts on any object that is in motion • The magnitude of the force needed to keep the …………….
Coefficients of Friction • The coefficient of friction is a ratio of the magnitude of the force of friction between two surfaces to the normal force between those surfaces.
Check Your Understanding A crate of fish of mass 18.0 kg rests on the floor of a parked delivery truck. The coefficients of friction ………………. • a horizontal force of 75.0 N [E] is applied to the crate? • if a horizontal force of 95.0 N [E] is applied? Answers: a) No movement because the Fapp < Fs b) FK = 72.3 N [backwards], a = 1.26 m/s2
Check Your Understanding A musician applies a horizontal force of 17 N [W] to an instrument case of mass 5.1 kg. The case slides across a table with an acceleration of 0.39 m/s2 [W]. What is the coefficient of kinetic friction between the case and the table? Answer: μK = 0.30