Coefficient of Friction

Created for CVCA PhysicsBy

Dick Heckathorn19 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

DefinitionsCoefficient of friction (µ) is defined as the force of friction divided by the normal force.

n

f

F

F

Fe on block

FN

Fe on block

FN

Ff

Ff

Surface μ

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

Weight Ford Explorer 26,000 N

dry - 1.07 wet - 0.95 ice - 0.005

Coefficient of frictionrubber on asphalt

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

Force of Surface on Explorer

Analysis – Block on Table

The Problem

What is the

coefficient of friction

of a block

sliding on a table?

36.048.12

5.4

N

N

F

F

N

f

Pull block at constant speedFind coefficient of friction (μ)Force of earth on block =Normal Force (FN) =Force of Friction (Ff) =

Analysis – Block on Table

Fe on B = 12.48 N

F on B = 4.5 N

FN = 12.48 N

F f = 4.5 N

Finding Coefficient of Friction of Block on Ramp

Created for CVCA PhysicsBy

Dick Heckathorn6 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.

396.0134.1

449.0

N

N

F

F

N

f

o59.21100

8.36sin 1

Finding coefficient of fricton μThe MeasurementsFinding the angleBlock sliding at constant speedFinding FN and Ff

Ff = 0.449 N

Fe on B = 1.22 N

36.8 cm

1 m θ

θ

FN = 1.134 N

That’s all folks!

Portland Less than More than Cement 30 mi/hr 30 mi/hr

Dry Road SurfaceNew, Sharp 0.8 - 1.2 0.7 – 1Traveled 0.6 - 0.8 0.6 – 0.75Traffic Polished 0.55 - 0.75 0.5 – 0.65

Wet Road SurfaceNew, Sharp 0.5 – 0.8 0.4 – 0.75Traveled 0.45 - 0.7 0.45 – 0.65Traffic Polished 0.45 - 0.65 0.45 – 0.6

Asphalt Less than More than or Tar 30 mi/hr 30 mi/hr

Dry Road SurfaceNew, Sharp 0.8 - 1.2 0.65 – 1Traveled 0.6 - 0.8 0.55 – 0.65Traffic Polished 0.55 - 0.75 0.45 – 0.65Excess Tar 0.5 – 0.6 0.35 – 0.6

Wet Road SurfaceNew, Sharp 0.5 – 0.8 0.45 – 0.75Traveled 0.45 - 0.7 0.4 – 0.65Traffic Polished 0.45 - 0.65 0.4 – 0.6Excess 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 SurfaceIce Smooth 0.1 – 0.25 0.07 – 0.2Snow Packed 0.3 - 0.55 0.35 – 0.55Snow Loose 0.1 – 0.25 0.1 – 0.2

Wet Road SurfaceIce Smooth 0.5 – 0.1 0.05 – 0.1Snow Packed 0.3 - 0.6 0.3 – 0.6Snow Loose 0.3 - 0.6 0.3 – 0.6

That is all, it is all!