LABORATORY NOTEBOOK
Organization of lab notebook
• Keep a table of contents at the beginning of the
notebook(about 2 pages)
• For each lab, start with the printed lab handout
from teacher (tape/glue it)
• Then include the laboratory report completed
according to the following format:
1. Title
• Place it on the top of the first page
• Write the name(s) of the person(s) doing the
experiment
• Date of when the experiment was performed
Friction Can Be a Real Drag
2. Objective/Purpose
• What are the main reasons you are
performing this experiment?
• Be specific...don't just restate the title
or copy the generic objectives from the
given lab packet or a textbook
• One or two sentences
2. Objective/Purpose
In this laboratory experiment, I will
a. determine how does the force of friction
(Fk) depends on the force of gravity (Fg)
on an object when the object slides over a
“smooth” horizontal surface and...
b. determine how Fk varies with the area of
contact between two smooth, flat
surfaces when all other factors are
controlled
3. Equipment
• A bulleted list of all the materials and
equipment you will use in this experiment
3. Equipment
Wooden blocks
 Spring balance
 Ruler
 String

4. Procedure
• In your own words, write a brief summary of
the procedure in paragraph format
• Do not include lengthy, detailed directions.
• A person who understands physics should be
able to read this section and know what you
are doing
4. Procedure
I first determined the mass of each
wooden block using a spring balance
I measured the force of kinetic friction of
one block, two blocks, three blocks, and
four blocks stacked on top of each other
(You can also include a picture)
1.
2.
4. Procedure
3.
I measured the force of kinetic friction of
the wooden blocks arranged the way so
the surface area of the contact between
the blocks and the surface was doubled,
tripled and quadrupled (while keeping the
force of gravity of the blocks constant)
5. Data
• Record all the measurements and observations
you made during the lab and put them into
data tables
• All the data tables MUST have titles, quantities
and units
• Do not erase when recording data; simply draw
a single line through a mistake and record the
new value next to it.
5. Data
• Record all the measurements and observations
you made during the lab and put them into
data tables
• All the data tables MUST have titles, quantities
and units
• Do not erase when recording data; simply draw
a single line through a mistake and record the
new value next to it.
5. Data
Table 1:
Force Of Sliding Friction Of Wooden Blocks
5. Data
Table 2:
Force Of Friction as the Surface Area is Varied
6. Analysis and Results
• DO the calculations and put the results into
new tables
• Do the graphs either by hand on the graph
paper or by using MS Excel
• Each graph MUST include title, appropriate
labels, quantities and units
• Determine sources of error and calculate
absolute and relative error
Calculations for the slope of the line:
slope = coefficient of kinetic friction= Fk2 – Fk2 = ....
Fg2 – Fg1
Determining the coefficient of kinetic fiction
Table 3:
Determining the coefficient of
kinetic fiction
Fk1
(N)
Fk (N)
Fk2
(N)
Fg1
(N)
Fg2
(N)
Slope =
Coefficient of
kinetic friction
Fg(N)
ABSOLUTE and PERCENTAGE (RELATIVE) ERROR
 If
you want to compare how
ACCURATE your measurement in a lab
was to the accepted (known) value of
whatever you measured
For example:
You found out that the Coefficient Of Kinetic
Friction was 0.21
How accurate was your measurement to
the “real” value for coefficient of the
kinetic friction between the wooden block
and the desk??
ABSOLUTE and PERCENTAGE (RELATIVE) ERROR
How accurate was your measurement to the “real”
value for coefficient of the kinetic friction
between the wooden block and the desk??
You found out that the Coefficient Of Kinetic
Friction (Experimental Value)
The Coefficient Of Kinetic Friction from a
textbook or the internet (Actual Value) was
found to be
ABSOLUTE ERROR
PERCENTAGE (RELATIVE) ERROR
8. Conclusion
• Data is summarized
• Any derived relationships are mentioned
• Relate data to your hypothesis/purpose
• Reference your results
• Do the data and the results support your
hypothesis/purpose?
• Explain, if you did the same experiment in
the future, how would you avoid
experimental errors?
8. Conclusion
Based on my experiment, it was found out that
1.
the force of friction between an object and a smooth horizontal surface is
depended on the force of gravity(weight), AND
2.
it is independent of the surface area of contact between the object and the
surface.
The reasons for #1:
It was determined that when Fg was increased Fk also increased always by the same
factor. This factor is µ, and its value was found out to be 0.20 (see Table 1 and
2).
This value represents about 28% error when compared to the actual value (taken
from the textbook).
The reasons for #2:
It was determined that when the contact area between two smooth surfaces was
increased, Fk stayed the same meaning that Fk is independent of the surface
area of an object and a surface (see Table 3).
The large percentage error could be due to poor precision of the measuring
equipment (spring scales) as well as due to unevenness of the wooden blocks
that were used in the experiment.
To avoid such a large error in the future, a digital scale and high quality blocks could
be used.