1 / 68

Ch. 11, Vibrations and Waves

Ch. 11, Vibrations and Waves. A repeated motion, like the pendulum on a clock, is called periodic motion . Another exp is a mass on a spring. At the equilibrium position, the speed is at its maximum. At the equilibrium position, the acceleration is zero.

dinos
Download Presentation

Ch. 11, Vibrations and Waves

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Ch. 11, Vibrations and Waves

  2. A repeated motion, like the pendulum on a clock, is called periodic motion. • Another exp is a mass on a spring.

  3. At the equilibrium position, the speed is at its maximum. • At the equilibrium position, the acceleration is zero.

  4. At maximum displacement, spring force and acceleration reach a maximum.

  5. In an ideal system, the spring would go back and forth forever. • Friction causes a damping force that causes an oscillator to stop.

  6. In simple harmonic motion (SHM), restoring force is proportional to displacement.

  7. Hooke’s Law • Felastic = -kx • Negative sign indicates that the direction of the spring force is always opposite the direction of the displacement.

  8. SHM takes place back and forth along the same path.

  9. A stretched or compressed spring has elastic potential energy. • This can be released as kinetic energy.

  10. Pendulums • Contain a mass called a bob, attached to a fixed string.

  11. The restoring force on a pendulum is a COMPONENT of the bob’s weight. • The net force acting on a bob is Fg,x = Fg*sin(theta)

  12. As long as a pendulum stays within an angle of about 15 degrees, it is a very good example of SHM.

  13. When is Vel and Acc greatest? 0?

  14. Page 374, Figure 5, Gravitational Potential increases as a pendulum’s displacement increases. • Table 1, page 375.

  15. Amplitude The maximum displacement from the equilibrium position.

  16. Period the time to make one complete cycle.

  17. The number of cycles per unit time = Frequency. Unit = s-1

  18. f = 1/T or T = 1/f • T = 2*pi*(L/9.81)^.5

  19. Mass-Spring system in SHM • Give equation.

  20. WAVES • What are Waves? Discussion

  21. A wave is the motion of a disturbance.

  22. The MEDIUM is the physical environment through which a wave travels.

  23. Most waves are called Mechanical Waves. They need a medium to travel through. • Some waves do not require a medium, like electromagnetic radiation waves.

  24. Pulse Wave: One wave • Periodic Wave: Continuous waves

  25. Sine waves describe particles vibrating with SHM.

  26. If you look at one point, it goes up and down with SHM.

  27. Transverse waves The particles vibrate perpendicularly to the direction the wave is traveling.

  28. A Waveform can show what a wave is doing.

  29. Trough A low point • Crest A high point • Wavelength (lambda)  Distance between a whole cycle.

  30. Longitudinal Wave The particles vibrate PARALLEL to the wave’s motion.

  31. Graph = Density vs. Displacement

  32. Frequency = number of complete waves that pass a certain point per second. • Period = How long it takes ONE wave to pass a certain point.

More Related