STATIC FRICTION LAB
PURPOSE  To determine the
coefficient of static friction of various surfaces.
HYPOTHESIS  Estimate the
coefficient of static friction of the various surfaces
EQUIPMENT  Block of wood
(brick), friction board with different surfaces, spring scale
PROCEDURE
Part One
1. Determine the mass of
the block.
2. Attach the spring scale
to the block.
3. Place the block on one
of the surfaces.
4. Pull the spring scale
until the block just begins to move. Determine the maximum amount of pull that
can be used WITHOUT moving the block.
5. Record this value and
repeat several times.
6. Complete the same
testing procedure for each of the surfaces.
RESULTS
Mass of the block:
_______________ Kg
Weight of the block: _____________ N
PART ONE
TRIAL NUMBER  MAXIMUM PULL KG
SUR FACE TYPE 
TEST 1 
TEST 2 
TEST 3 
TEST 4 
TEST 5 
AVE 
STATIC FORCE N 
BARE WOOD 







PAINT 







PAPER 







PLASTIC 







PART ONE
SURFACE TYPE 
MAX STATIC FORCE N 
NORMAL FORCE N 
COEFFICIENT OF STATIC FRICTION MU m 
BARE WOOD 



PAINT 



PAPER 



PLASTIC 



PART TWO
1. Place the block on one of the surfaces.
2. Raise one end of the board until the block just starts
to slide.
3. Measure the height raised.
4. Determine the angle of the incline.
5. Determine the Tangent of the maximum angle of incline.
LENGTH OF BOARD __________
M
TRIAL NUMBER  MAXIMUM HEIGHT METERS
SUR FACE TYPE 
TEST 1 
TEST 2 
TEST 3 
TEST 4 
TEST 5 
AVE HT M 
MAX ANGLE 
BARE WOOD 







PAINT 







PAPER 







PLASTIC 







PART TWO
SURFACE TYPE 
COEFFICIENT OF
STATIC FRICTION MU m 
TANGENT OF THE
MAXIMUM ANGLE OF INCLINE 
PERCENT
DIFFERENCE 
BARE WOOD 



PAINT 



PAPER 



PLASTIC 





AVERAGE 

Part Three
Surface Area and Friction
TRIAL NUMBER  MAXIMUM PULL KG
SUR FACE TYPE 
TEST 1 
TEST 2 
TEST 3 
TEST 4 
TEST 5 
AVE 
STATIC FORCE N 
m 
Bottom 








Side 








End 








% Diff = 100 (Bottom – other) / Bottom
Part Four
TRIAL NUMBER  MAXIMUM PULL KG

TEST 1 
TEST 2 
TEST 3 
TEST 4 
TEST 5 
AVE 
STATIC FORCE N 
Brick 







1 Block 







2 Block 







3 Block 







4 Block 







5 Block 








Total Mass Kg 
Normal Force N 
STATIC FORCE N 
m 
Brick 




1 Block 




2 Block 




3 Block 




4 Block 




5 Block 




ANALYZED DATA
PART ONE
A. Complete each data
table.
NOTE  The Weight = m
g Weight = Fn
mu
= f / Fn
C. Determine the percent
differences between the estimated and the actual coefficients of static
friction.
PART TWO
A.
Complete each
data table.
B.
Calculate the
percent difference
Percent
Diff = 100 (Pt 1 – Pt 2) / Pt 1
PART THREE
A.
Complete the data
table
B.
Find the percent
difference between orientations
% Diff = 100 (Bottom – other) / Bottom
PART FOUR
A.
Complete the data
tables.
B.
Make a graph of
the number of Normal Force (Xaxis) versus the Frictional Force (YAxis).
C.
Sketch the graph
and determine the slope, yintercept and correlation coefficient.
CONCLUSION
1. What causes static
friction?
2. What does the
coefficient of static friction actually represent?
3. Rate the surfaces from
the smallest to largest coefficient of static friction.
4. Explain how the tangent
of the maximum angle attained without sliding compares to the coefficient of
static friction.
5. Explain how changing
the surface area changes the coefficient of static friction.
6. Explain how changing the normal force changes the coefficient of static friction