1. Statics and Friction

2. Our Friction Lab Data – Erratic Trend – Upward F Frict ~ F normal F Frict = µ∙ F normal µ - Coefficient of Friction

3. Slope = Δy / Δx = Δ Friction / Δ Normal = µ F Frict = µ∙ F normal Coefficient of Friction

4. A 10 pound block is pulled by a 5 pound block which is hanging from a pulley. If the coefficient of friction is.6, will the blocks slide? Normal force = F N = 10 pounds Tangential force = F T = 5 pounds Maximum force of friction = F F = µ∙F N =.6∙10 = 6 pounds Force of String = F T = 5 is too little to move A 70° Our Friction Lab

5. Components

6. A 1000 Pound Car on a Hill in Manayunk If the coefficient of friction is.4, will the car slip?

7. Geometry Trig sin 20 = opp/hyp = F T /1000 cos 20 = adj/hyp = F N /1000 Algebra F T =1000∙ sin 20 = 342 pounds F N =1000∙ cos 20 = 940 pounds Physics Friction = F F = µ∙F N =.4 x 940 = 376 pounds Suppose the hill is inclined with an angle of 20° with the horizontal. ( µ=.4) Car does not slide