Experimenting with Pendulums

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. His discovery of the periodic motion of pendulums paved the way for the invention of clocks and standardization of time. 

Students learned that a pendulum consists of a pivot point with a rope or wire attached to it and a mass  (“bob”) 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. Students also learned that some common day items they might use or have seen, such as metronomes and grandfather clocks use pendulums.  

For their activity, students investigated effect of three factors – the mass of the bob, the length of the chain, and the angle with which the bob of the pendulum was released from – on the period of the pendulum, using pendulums they constructed.  They were surprised to learn that only length caused the period to change:  a longer length correlated to a longer period. Students also learned that gravity works on different masses in the same way, so mass is not a factor in the period of the pendulum.

Additional Information:

To experiment with virtual pendulums at home, check out:

http://phet.colorado.edu/sims/pendulum-lab/pendulum-lab_en.html

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

https://www.youtube.com/watch?v=yVkdfJ9PkRQ

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