Swinging Yo-Yo icon
Student Guide

Swinging Yo-Yo

Understanding the period of a swinging object

What variables affect the period of a pendulum?

This resource was originally published in PhysicsQuest 2010: Force!

What variables affect the period of a pendulum?

  • 2 yo-yos
  • 2 cans “gravity testing material”
  • Timer/clock with seconds
  • Sheets of graph paper
Intro

Pendulums are everywhere. Because the swing of a pendulum is so regular they are often used to time things like in a clock or a metronome. But what changes how a pendulum swings? Why is it so regular? This experiment will help you find out.

Before the Experiment
  • To start off...
    1. To start off, look at the materials you have in front of you and play with them a bit. What kind of things can you do with the stuff you have?
    2. Use the yo-yo (or yo-yos) as a pendulum and start exploring how it swings.
    3. Think about what the independent variables could be for this experiment. List variables you might be able to change with the materials you have in front of you.
    4. Using the information you wrote down above, design an experiment to test how one variable affects a pendulum’s swing. What will you change? How? By how much? What will you measure? How many trials will you do (might I suggest more than one)? Once you have this data, what will you do with it? What will it teach you? How will you analyze it?
  • Procedures

    The “period” of the pendulum is the TIME it takes for the object at the bottom of the pendulum to get back to the position it started from. Time will be your dependent variable.

    The blue line traces the period of this pendulum. You can time from when the object leaves the middle, travels to the right, through the middle, to the left, and back to the middle, making a full revolution through its range of motion.



Setting Up
During the Experiment
Collecting Data
  • Collect your data on what you want to test

    Collect your data on what you want to test and how you’re testing.

  • Think about the best way to collect, record, and represent your data.

    Think about the best way to collect, record, and represent your data. Make sure all group member input is taken into account and all members of your group have an active role in the experiment.

Analyzing Data
  • What were your results?

    What were your results?

    • Make a table where you have the values for your independent variable in one column and the corresponding values for the dependent variable in the other. Do you notice any patterns?
  • Try graphing your data

    Try graphing your data. Remember, the independent variable always goes on the “x” axis and the dependent variable goes on the “y” axis. Do you see any patterns now?

  • What claims can you make?

    What claims about what affects the period of the pendulum can you make based on your data?

Conclusion
  • What further questions do you have based on your data?

    What further questions do you have based on your data?

  • What follow up experiment could you conduct?

    What follow up experiment could you conduct to collect data about this question?

Join your Society

If you embrace scientific discovery, truth and integrity, partnership, inclusion, and lifelong curiosity, this is your professional home.