Science Journal Blog Entry 5: Physical Science Inquiry

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• Which pendulum will come to rest more quickly—
• a lighter pendulum or heavier pendulum?
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   Using the three different sized washers and the string provided in the course science kit I create a simple pendulum setup in my garage (appendix A). To start the investigation I tied a loop at one end of the string. This loop was then placed around a short length of half inch PVC pipe to become the pivot point for the pendulum. The PVC pipe was then clamped tightly into place using a vice. Each washer (bob) was fixed onto the length of string with a simple clove hitch to hold the washer in place. Care was taken to ensure that all three washers (bobs) were fixed to the string at the same length from the pivot point (44 centimeters). I then collect 5 trials of data for each of the three washers by raising the washer to a set height (amplitude) while simultaneously releasing the washer and starting the stopwatch to measure the time it takes for the washer (bob) to come to a complete stop back at the origin. 

    During this guided inquiry investigation I was able to collect reliable data (see table below) needed to show how changing the mass of a pendulum bob changes the length of time a pendulum with oscillate. As the mass of the pendulum increased so did the length of time needed for the pendulum to come to rest back at the origin. This is as I expected, but was able to discover more information about how a pendulum rotate during oscillation. I did encounter a few interference issues with the pendulum length being too long, but I was able to make the needed adjustments. 

    If I were to complete this investigation with my students I would need to cover some key vocabulary ahead of time. I would also want to discuss how to establish experimental controls to ensure reliable data is collected. Possible fun extensions could have students create a life size pendulum or brainstorm how this investigation could be completed on a playground. 

Appendix A- Pendulum setup

Data collected.