The document discusses how to determine the variables that affect the period of a pendulum. It explains that the length of the pendulum, measured from the point of suspension to the center of mass of the bob, affects its period. The variables that do affect the period of a pendulum are its length and mass. Students should analyze their data to determine if changes in these variables resulted in changes to the period and whether their results match the equation that describes the relationship between variables and period of a pendulum.

1. Thinking Scientifically
Finding the variable(s) that affect the
period of a pendulum

2. A simple pendulum consists of a string, cord, or wire
that allows a suspended mass to swing back and forth.
The categorization of "simple" comes from the fact
that all of the mass of the pendulum is concentrated
in its "bob" - or suspended mass.
As seen in this diagram, the length of
the pendulum is measured from the
pendulum's point of suspension to
the center of mass of its bob. Its
amplitude is the string's angular
displacement from its vertical or its
equilibrium position. If a pendulum is
pulled to the right side and released to
swing back and forth, its path
traces our a sine curve as shown
below.

3. Which variable(s)
COULD affect the period
of a pendulum?

4. The variables that DO affect the period
of the pendulum are…

5. How do you know?
• Look at your data
• Which variables had an effect on the period of
your pendulum?
• How do you know it’s enough of a change?
• Why weren’t all the times for the trials exactly
the same?
• Do your results match up with what the
equation for this relationship says?

7. RERUN
Writing an effective science
conclusion

8. R.E.R.U.N.
Recall what you did during this lab
Explain why you did this lab and what you were trying to find out
Reflect on the lab’s meaning. If you predicted, did it match your
hypothesis? Was your hypothesis wrong? Why?
Uncertainty (errors that were in the lab that you could not control
[aka: weather problems, measurement mistakes, etc.] or errors that
you came across during the lab that you could fix for the next time you
perform this lab)
New questions or new discoveries (normally you put at least three)

9. R.E.R.U.N.
Recall what you did during this lab: How well did they summarize? Did you get a basic
review about materials and methods used? Did the writer explain how the lab was set-up
and completed? (rate on a scale of 1-5)
Explain why you did this lab and what you were trying to find out: Did they state the
purpose of the lab? Were you able to understand why the lab was done?
(rate on a scale of 1-5)
Reflect on the lab’s meaning. If you predicted, did it match your hypothesis? Was your
hypothesis wrong? Why?: What was their hypothesis? Was it correct? Were there any
surprises from the results? Was there any relationships that came from this lab?
(rate on a scale of 1-5)
Uncertainty (errors that were in the lab that you could not control [aka: weather
problems, measurement mistakes, etc.] or errors that you came across during the lab
that you could fix for the next time you perform this lab): What went wrong? Why wasn’t
your data perfect? Did they specify what kinds of problems occurred during the lab?
(rate on a scale of 1-5)
New questions or new discoveries (normally you put at least three): Did they state at
least 3 questions and/or discoveries? (rate on a scale of 1-5)

10. Which variable(s) could affect
the period of a spring?

11. Do your results match the equation?