Printhttp://www.physicsclassroom.com/class/sound/Lesson-4/Forced-Vibration
http://www.met.reading.ac.uk/pplato/resources/h-flap/p5_3t.pdf
http://en.wikipedia.org/wiki/Vibration
http://www.math.utah.edu/~gustafso/f2009/forcedVibrationsResonance2008.pdf
http://www.newagepublishers.com/samplechapter/000591.pdf
http://www.britannica.com/EBchecked/topic/213174/forced-vibration
6th grade
8th grade
11th grade
12th grade
