[url=https://phet.colorado.edu/sims/pendulum-lab/pendulum-lab_en.html]Link to Simulation[/url] (requires flash)[br][br]Use this simulation to explore the behavior of two simple pendulums.[br][br][list=1][*]For small displacement angles, period is supposed to be independent of mass and amplitude (amount you pull the pendulum back). Is it true?[/*][*]How big does the amplitude need to be before this approximation breaks?[/*][*]Does the period ever depend on the mass?[/*][*]Grandfather clocks used to use a pendulum with a period of 2 second (1 second between "tick" and "tock"). How long was this pendulum?[/*][*]Can you determine the acceleration due to gravity on "planet X"?[/*][/list][br]Credits:[br]PhET Interactive Simulations[br]University of Colorado Boulder[br]https://phet.colorado.edu