1. Chapter 8 Vibrations and Waves Mr. Jean January 3 rd, 2012

2. The plan: n Video Clip of the day n Introduction to waves n Ways to transmit & transfer energy

3. Welcome Back: n Things to look forward to in 2012

4. Less end of world predictions compared to last year.: n There are only 6 popular end of world theories scheduled for 2012. n This is down from last year’s 9. n The most popular being December 21 st, 2012 – The end of the Myna calendar.

5. Total Solar Eclipse n It doesn’t happen that often !! n Next year, on November 13th, the Earth will witness a total solar eclipse

6. Closest known near miss: n A NASA team has discovered that next year will be our closest asteroid miss EVER. n The beast in question is named ‘433 Eros‘ and has been haunting our skies since its discovery in 1898. Come Jan 31st, if you’re looking in the right direction, you should be able to get a decent look.

7. Space Travel for a price: n Scheduled to kick off in 2012 is COMMERCIAL SPACE TRAVEL. Yes, that’s right. Come October 2012, tickets will be on sale for you to get your very own space cadet feeling. n However, at a cool $200,000.

8. And of course: n Physics 11 - Waves, light & sound. n Physics 11 – Quiz Chapter #5 & #6 n Science Fair n Exams!!! (woohoo?)

9. There are two ways to transmit information/energy in our universe: 1) Particle Motion 2) Wave Motion

10. Light and Sound Both are vibrations of energy and they share some similar wave properties.

11. Random interesting question: n The Earth’s atmosphere is more dense than Mars. If you and your friend stand at opposite ends of a football field. You talk just loud enough to hear each other. If you talked at the same volume, however you and your friend were on Mars what would happen to your friends voice? n How do you know?

12. 1.VIBRATION OF A PENDULUM n Examples: Metronome, Grandfather clock, etc.. n n T is the period, the time for one vibration. n n l is the length of the pendulum. n n g is the acceleration due to gravity. n n (Galileo discovered this.) n n Period (T) is independent of the bob mass.

13. n Pendulum Uses: When oscillations are small, the motion is called simple harmonic motion and can be described by a simple sine curve.

14. Simple Harmonic Motion: n Any motion that repeats itself precisely over equal periods of time when generated by a linear restoring force in accordance to Hooke’s Law.

15. Common Examples: n Sinusoidal equations n Pendulums n Weights on a spring n All examples of uniform circular motion with constant velocities. u Ferris wheels u Tires u A car turning around a circular track etc….. n Pistons in an engine n Musical instruments n Standing waves n Record players

16. Piston Example:

17. SHM: Tarzan / Grandfather Clock

18. 2.WAVE DESCRIPTION Frequency ( f ) is the number of vibrations per unit of time made by the vibrating source. Units - cycles per second 1/s Hertz (Hz)

19. Picture of a Transverse Wave Crest Trough Wavelength A A - Amplitude

20. Distance between adjacent crests in a transverse wave. Distance a wave travels during one vibration. in meters Wavelength ( )

21. n The period (T) of a vibration is the time required to make one vibration. n The (T) of a wave is the time required to generate one wave. n The period (T) of a wave is the time required to generate one wave. n It is also the time required for the wave to travel one wavelength.

22. Frequency Period

23. In symbolic form or

24. Example Question: n A mass suspended from the end of a spring vibrates up and down 24 times in 36 seconds. What is the frequency and period of the vibration?

26. In class work: n Read Pages u P. 345 - 353