1. Pendulum Clock By: Junho, Dh

2. What is this invention -Pendulum Clock -Pendulum -16 th century

3. History 1582 – Galileo fixed period 1656- Dutch Scientist Christian Huygens 1880s- The grandfather clock 1921- Designs improve

4. Purpose Save time Keep promise/meeting Accurate time

5. How it works? Swing back and forth Time base – gears Small gear rotate Each gear, face of the clock

6. How simple machine… Controlled force Self working

7. One World Sociable Keep Meetings and promises Friend ship

8. Advantages Sociable Keep time well Accurate time

9. Disadvantage Need battery/ resource When time is not set

10. Bibliography -History of the pendulum clock." Grandfather clocks info: Facts about long case clocks. grandfather clocks guide, n.d. Web. 20 Apr. 2011. http://www.grandfather-clocks-guide.info/history-of-the-pendulumqs- clock.html. http://www.grandfather-clocks-guide.info/history-of-the-pendulumqs- clock.html -Huygen’s principle. Cambridge Physics Huygen’s principle. http://www- outreach.phy.cam.ac.uk/camphy/xraydiffraction/xraydiffraction4_1.htm. April 19 th.http://www- outreach.phy.cam.ac.uk/camphy/xraydiffraction/xraydiffraction4_1.htm -Katzenback, Jason. Are you Blogging with Purpose? (If not 5 ways to fix it). Copyblogger Are you blogging with purpose? (If not, 5 ways to fix it) http://www.copyblogger.com/purposeful-blogging/. April 19, 2011 http://www.copyblogger.com/purposeful-blogging/ - Lilley,Stephen. How a clocks work. Ehow How a clocks work -Pendulum Clock. Wikipedia Pendulum Clock http://en.wikipedia.org/wiki/Pendulum_clock\ -Simple machine. Science Learning simple machine. http://www.fi.edu/qa97/spotlight3/spotlight3.html. April 19, 2011 http://www.fi.edu/qa97/spotlight3/spotlight3.html -U+2212 MINUS SIGN. Decodeunicode U+2212 MINUS SIGN. http://www.decodeunicode.org/u+2212. April 19, 2011 http://www.decodeunicode.org/u+2212

11. THANK YOU