Object(s)
Mass (kg)
Force of Gravity (N)
F
g
=m(9.8 m/s
2
)
Normal Force (N)
Cancels gravity in this
situation so same value
as F
g
Static Friction Force
(N)
1 box
Man
Girl + 1 Box
Trash can

Man + 1 box
Box + trashcan
Man + trashcan
Refrigerator
IF THE OBJECT DOES NOT MOVE EVEN WITH 500 N of force, place an X through the data as it means we cannot find the static friction’s maximum
value.
Use the data to construct a
Static Friction vs. Normal Force.
●
Title your graph
Static Friction vs. Normal Force
●
Label your x-axis
F
N
with units
N
; our independent variable (x) will be Normal Force.
o
This should be a positive number, and the same magnitude (size or number) as the Force of
Gravity
●
Label your y-axis
F
sf
with units
N
; our dependent variable (y) will be the Static Friction Force
o
Ignore direction for this graph, all values should be positive values.
●
Draw a line of best fit using the points
●
Record the m (slope) and b (y-int) value
Write your y=mx+b equation: ________________________________
The slope here represents our
coefficient of friction (µ
s
)
which you can think of as a measure of the stickiness
between two surfaces. It is a measure of the ratio of friction and normal force. The subscript ‘s’ next to the µ indicates
we are talking about static friction and an object not in motion. We can specify it as the formula below.
F
sf
= µ
s
(F
N
)
Static Friction = coefficient of static friction x Normal Force
Your slope (m value) in the graph is the coefficient.
Write it down:
µ
s
= _______________
1.
Using your coefficient from the graph (slope), multiply it by the normal force for the box (490 N). What do you
get? Show your work.