Tick Tock… Pendulum Motion

Pendulums:  To and Fro We Go

Today’s lesson focused on pendulums.   The motion of pendulums was one of the many phenomena investigated by the famed scientist Galileo over 400 years ago and what he learned about them had a huge impact on the history of technology. The periodic motion of pendulums allowed for the invention of clocks and the standardization of time, and they still have many uses in modern society.

Students saw that a pendulum consists of a pivot point with a rope or wire attached to it and a mass on the end. The time it takes the pendulum to make one full oscillation back and forth is called the period. Here, gravity is the only force working on the pendulum. If we took the same pendulum and put it on the Moon, the pendulum would have a slower period due to less gravitational force. Some examples of items that use pendulums are metronomes and grandfather clocks.

For the activity, students constructed their own pendulums and then changed the length of the pendulum and measured how long the period was for the different lengths. They noticed a pattern: a longer length correlated to a longer period. They used this pattern to predict the length of the period for an even longer chain length. Predicting how a system will react if the variable is changed is an important scientific skill.

Students really enjoyed this activity!

Additional Information:

To experiment with virtual pendulums at home, check out:


This video shows some of the cool patterns that a group of pendulum waves can make!



Información adicional:

Para experimentar con péndulos virtuales en tu hogar, revisa este link:


El siguiente video muestra algunos de los efectos que un grupo de péndulos puede generar:



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Dr. Maureen Griffin

Maureen earned a Ph.D. in Chemical and Biomolecular Engineering from the University of Pennsylvania in 2003. While at Penn, she developed a novel micro-mechanical technique called micropipette peeling to investigate the role of muscle cell adhesion in normal and diseased skeletal muscle cells. After graduating, Maureen worked full time as a post-doctoral researcher and then a staff scientist a SelectX Pharmaceuticals. She joined the teaching staff in 2008 and was excited to be made an executive staff member in 2009. Maureen also continued to consult part time for SelectX until her daughter's birth in 2009; now she is focused on Science from Scientists and, of course, her children. Maureen uses her spare time to read, blog, cook, and renovate her house.

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