Coefficient of Friction Created for CVCA Physics By Dick Heckathorn 11 November 2K + 4

Table of Contents 3 Coefficient of Friction Table 4 Force of ground on vehicle 5 μ of block sliding on table 7 μ of block sliding down ramp

Definitions FN FN Ff Ff Fe on block Fe on block Coefficient of friction (µ) is defined as the force of friction divided by the normal force. FN FN Ff Ff Fe on block Fe on block

Surface μ Rubber on asphalt, dry 1.07 Rubber on asphalt, wet 0.95 Rubber on ice 0.005 Rubber on concrete, dry 1.02 Rubber on concrete, wet 0.97 Steel on steel – dry 0.41 Steel on steel – lubricated 0.12 Steel on ice 0.01

Force of Surface on Explorer Coefficient of friction Weight Ford Explorer 26,000 N Coefficient of friction rubber on asphalt dry - 1.07 wet - 0.95 ice - 0.005 Fapplied dry = 1.07 x 26,000N = 27,820 N Fapplied wet = 0.95 x 26,000N = 24,700 N Fapplied ice = .005 x 26,000N = 130 N

Analysis – Block on Table The Problem What is the coefficient of friction of a block sliding on a table?

Analysis – Block on Table Normal Force (FN) = Force of earth on block = Pull block at constant speed Force of Friction (Ff) = Find coefficient of friction (μ) FN = 12.48 N F f = 4.5 N F on B = 4.5 N Fe on B = 12.48 N

Finding Coefficient of Friction of Block on Ramp Created for CVCA Physics By Dick Heckathorn 6 December 2K+3

Analysis – Block on Ramp What is the coefficient of friction of a block sliding on a ramp?

Analysis – Block on Ramp Apparatus - Meter sticks (2) - Block with grove to fit over meter stick - scales to find weight of block

Analysis – Block on Ramp Procedure Place block on meter stick. Lift the meter stick until the block slides down the ramp at constant speed. Determine the angle of the meter stick with horizontal. Calculate the coefficient of friction.

Block sliding at constant speed Finding coefficient of fricton μ The Measurements Finding the angle Finding FN and Ff FN = 1.134 N θ Ff = 0.449 N 36.8 cm 1 m θ Fe on B = 1.22 N

That’s all folks!

Portland Less than More than Cement 30 mi/hr 30 mi/hr Dry Road Surface New, Sharp 0.8 - 1.2 0.7 – 1 Traveled 0.6 - 0.8 0.6 – 0.75 Traffic Polished 0.55 - 0.75 0.5 – 0.65 Wet Road Surface New, Sharp 0.5 – 0.8 0.4 – 0.75 Traveled 0.45 - 0.7 0.45 – 0.65 Traffic Polished 0.45 - 0.65 0.45 – 0.6

Asphalt Less than More than or Tar 30 mi/hr 30 mi/hr Dry Road Surface New, Sharp 0.8 - 1.2 0.65 – 1 Traveled 0.6 - 0.8 0.55 – 0.65 Traffic Polished 0.55 - 0.75 0.45 – 0.65 Excess Tar 0.5 – 0.6 0.35 – 0.6 Wet Road Surface New, Sharp 0.5 – 0.8 0.45 – 0.75 Traveled 0.45 - 0.7 0.4 – 0.65 Traffic Polished 0.45 - 0.65 0.4 – 0.6 Excess Tar 0.3 – 0.6 0.25-0.55

Less than More than Gravel 30 mi/hr 30 mi/hr Dry Road Surface Pack, Oiled 0.55 – 0.85 0.5 – 0.8 Loose 0.4 - 0.7 0.4 – 0.7 Wet Road Surface Pack, Oiled 0.4 – 0.8 0.4 – 0.6 Loose 0.45 - 0.75 0.45 – 0.75

Less than More than Gravel 30 mi/hr 30 mi/hr Dry Road Surface Ice Smooth 0.1 – 0.25 0.07 – 0.2 Snow Packed 0.3 - 0.55 0.35 – 0.55 Snow Loose 0.1 – 0.25 0.1 – 0.2 Wet Road Surface Ice Smooth 0.5 – 0.1 0.05 – 0.1 Snow Packed 0.3 - 0.6 0.3 – 0.6 Snow Loose 0.3 - 0.6 0.3 – 0.6