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# Periodic Motion

Periodic Motion. Simple Harmonic Motion and Waves. Repetitive Motion. Period – time per occurrence T : Measured in seconds (s) Frequency – occurrences per time f : Measured in Hertz (Hz) How are they related?. Repetitive motion things that have a period

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## Periodic Motion

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1. Periodic Motion Simple Harmonic Motion and Waves

2. Repetitive Motion Period – time per occurrence T : Measured in seconds (s) Frequency – occurrences per time f : Measured in Hertz (Hz) How are they related? Free Template from www.brainybetty.com

3. Repetitive motion • things that have a period What objects exhibit this harmonic motion? • Pendulum • Planets/Circular Motion • Mass on a Spring • Waves Free Template from www.brainybetty.com

4. T W PENDULUM The forces that act on a pendulum bob are… • Weight • Tension Do they cancel out? No, the net force causes the bob to move. SF Free Template from www.brainybetty.com

5. q L m The overall relationship that was found is PENDULUM What can we measure to mathematically describe a pendulum’s motion? • Length (L) • Mass (m) • Amplitude (q) • Period (T) Free Template from www.brainybetty.com

6. q L m PENDULUM A 3.0 g steel ball is attached to a 1.2 meter string. A) How long will it take for the ball to make one complete cycle? B) What is the frequency of the pendulum. C) The same system was used on planet X. The period was 2.0 s. How big is gravity on this planet? Free Template from www.brainybetty.com

7. Waves

8. Waves What are some examples of waves? WAVE DEFINITION • A disturbance that propagates through a medium. • Waves carry energy from one place to another Free Template from www.brainybetty.com

9. Waves 2 Basic Types of Waves Transverse The disturbance is perpendicular to the direction of propagation Longitudinal The disturbance is parallel to the direction of propagation LIGHT S-WAVES SOUND P-WAVES Free Template from www.brainybetty.com

10. Waves CREST l • Crest & Trough • Wavelength • Amplitude AMPLITUDE A WAVELENGTH TROUGH Free Template from www.brainybetty.com

11. Waves Waves do not accelerate How do we find speed? • v=d/t • v=l/T • v=fl How do you change the speed of a wave? The speed of light, c = 3.00 x 108 m/s This is a very special number in physics. What is the frequency of red light if the wavelength is 700 nm? Free Template from www.brainybetty.com

12. Waves Sample Problem In the ocean, a boat uses sonar to determine the depth to the ocean floor. The speed of the sonar is 1400 m/s in water. If the boat receives the signal 8 seconds after sending, how deep is the ocean? Free Template from www.brainybetty.com

13. Waves Sample Problem… continued If the frequency of the sonar signal is 30,000 Hz, what is the length of one wave? Free Template from www.brainybetty.com

14. Waves • Boundaries • Fixed • Open Free Template from www.brainybetty.com

15. Waves • Principle of Superposition • Standing waves Free Template from www.brainybetty.com

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