SPH4U Lab #1 – Coefficients of Friction
Purpose : To determine the coefficient of static friction between a calculator and your
textbook or binder.
Your task is to,
1) Design an experiment that determines the coefficient of static friction of your
calculator without using a spring scale,
2) Carry out your experiment and record your observations, and
3) Answer the discussion questions in order to write a formal lab report.
Background Information and Hints
This task involves measuring force without using a spring scale. You have to use the only force
that you have readily available to you to help you.
HINT #1: Use gravity to help you determine the coefficient of static friction.
HINT #2: Problem solving often means working backwards, if you need μS consider finding FS
and FN first.
HINT #3:Other than the obvious use of the calculator and textbook you may need to use a
protractor.
Discussion Questions
1) When finding the coefficient of static friction in this manner, does the mass of the
calculator matter? Explain.
2) What was crucial about the coordinate system that you defined? Explain.
3) Which of Newton’s Laws did you use? Be specific.
4) Would the coefficient of friction you found be the same if the textbook had been
horizontal and you had used a spring scale? (Assume the spring scale is totally accurate
and you use it perfectly) Explain.
5) Prove using your net force statements that the acceleration is zero when the whiteboard
is horizontal.
Assessment
Experiment Design
Does the experiment find what it is required to?
Are all the variables controlled properly?
/10
Observations and Results
Did you find the correct data?
Does your math make sense?
/10
Conclusion and Discussion Questions
Is your conclusion complete and logical?
Are all the discussion questions answered?
Are the discussion questions answered correctly?
/10