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

2. 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

3. 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

4. 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

5. Force of Surface on Explorer Coefficient of friction
Weight Ford Explorer 26,000 N
Coefficient of friction
rubber on asphalt
dry wet ice
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 = N

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

7. 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 = N
F f = 4.5 N
F on B = 4.5 N
Fe on B = N

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

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

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

11. 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.

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

13. That’s all folks!

14. Portland Less than More than
Cement 30 mi/hr 30 mi/hr
Dry Road Surface
New, Sharp – 1
Traveled – 0.75
Traffic Polished – 0.65
Wet Road Surface
New, Sharp 0.5 – – 0.75
Traveled – 0.65
Traffic Polished – 0.6

15. Asphalt Less than More than
or Tar 30 mi/hr 30 mi/hr
Dry Road Surface
New, Sharp – 1
Traveled – 0.65
Traffic Polished – 0.65
Excess Tar 0.5 – – 0.6
Wet Road Surface
New, Sharp 0.5 – – 0.75
Traveled – 0.65
Traffic Polished – 0.6
Excess Tar 0.3 –

16. Less than More than
Gravel 30 mi/hr 30 mi/hr
Dry Road Surface
Pack, Oiled 0.55 – – 0.8
Loose – 0.7
Wet Road Surface
Pack, Oiled 0.4 – – 0.6
Loose – 0.75

17. Less than More than
Gravel 30 mi/hr 30 mi/hr
Dry Road Surface
Ice Smooth 0.1 – – 0.2
Snow Packed – 0.55
Snow Loose 0.1 – – 0.2
Wet Road Surface
Ice Smooth 0.5 – – 0.1
Snow Packed – 0.6
Snow Loose – 0.6