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Title: Need help with high school physics Friction Problem? Post by: julie7 on May 27, 2012 I push sideways on a box that masses 10kg that has a µ of 0.21 with the surface it sits on. It just begins to move, but I keep pushing with the same force. 5 seconds later it is 1.88m away. What is µk?
Title: Need help with high school physics Friction Problem? Post by: darwinian1 on May 27, 2012 static friction Fs = µFn = 0.21 * 10kg * 9.8m/s² = 20.58 N
This, then, is the applied force. In order to have travelled 1.88m in 5 s from rest with uniform acceleration, s = 1.88m = ½at² = ½ * a * (5s)² a = 0.15 m/s² This implies that the net force Fnet = ma = 10kg * 0.15m/s² = 1.5 N Then the kinetic friction Fk = Fapp - Fnet = 20.58N - 1.5N = 19.08 N kinetic µ = Fk / mg = 19.08N / 98N = 0.19 m/s² |