1. Waves and vibrations

2. Waves

4. Rogue wave

5. DEFINITION OF A WAVE

6. What is a wave? Is a disturbance that carries energy through matter or space It may or may not need a medium to move through, depending on the type of wave

7. Does a floating object move with the ripple?

8. Response Though the object will move as the ripple moves underneath, the extent of motion is much less than the wave it self

9. DEFINITION OF A MEDIUM

10. Medium Is any material through which a wave passes through Mediums move only a small amount compared to the distance the wave travels In general the medium returns to its original position, after the energy of the wave has passed

11. WHAT IS A VIBRATION?

13. An object vibrates when every portion of object repeats its motion along a simple path over a measurable length of time

14. Vibrations Involve transformations of energy Potential to Kinetic and back Think of a weight on the spring

15. Cause of a vibration Repeated application of forces on an object or medium

16. Another name for this type of motion is… Periodic Motion Any motion that repeats in a regular cycle

17. WAVES AND ENERGY

18. Waves transfer energy We know waves transfer energy because they do Work Water waves  boat, leaf, surfer… Sound waves  eardrum Light waves  on your eye, photographic film

19. Have you ever been hit by an ocean wave? Then you can get the idea that ocean waves can carry a lot of energy. Research is underway to find ways to harness energy of ocean waves Some of this research is being done at the university of Delaware

20. Energy from Ocean Waves June 2007 Wave Energy Bill Approved by U.S. House Science Committee Washington, DC [RenewableEnergyAccess.com] The U.S. House of Representatives Science and Technology Committee has approved, by voice vote, renewable energy legislation that would invest approximately $200 million in federal funds to advance research and development of wave energy technologies over the next four years.

21. Tsunamis Huge ocean wave caused by massive displacement of water

22. WHAT IS PERIODIC MOTION ? Simple Harmonic motion

23. Periodic motion is broadly defined Includes items moving in circles More interested in subsection that deals back and forth motion Simple harmonic motion

24. SIMPLE HARMONIC MOTION

25. Simple harmonic motion Examples: Slinky, swings, Bungee divers (hopefully) Object starts at equilibrium (balanced forces) As object is pulled away from equilibrium, the force trying to bring it back (restorative) increases Restorative force is directly proportional to displacement from equilibrium point Motion is periodic and repetitive

26. Damped Harmonic Motion The up and down motion fades over time Result of Friction, Air resistance or internal mechanisms Can be advantageous

27. TYPES OF WAVES

28. Mechanical Waves Waves that need a medium to move through A mechanical wave is a series of energy pulses that pass through matter Any vibration in matter is the source of a mechanical wave.

29. Examples of mechanical waves: Sound Water wave earthquake

30. DIFFERENT MECHANICAL WAVES MOTION

31. Mechanical waves Transverse waveLongitudinal wave

32. Transverse waves Waves in which the motion of the particles is perpendicular to the motion of the wave (energy) Vibration is perpendicular in direction to motion of energy The “wave” that travels around a stadium

33. Demo of transverse waves

34. Longitudinal waves Direction of force is parallel to direction of pulse Direction of vibration is parallel to direction of energy Compression and rarification in medium Example: Sound

35. Rarification A region in a medium where the density of matter is decreased Medium is stretched or thinned

36. WHAT DOES THE SECTION OF SLINKY WANT TO DO AS YOU COMPRESS IT?

37. Answer The rest of the slinky pulls back, until it reaches the equilibrium point If the slinky section overshoots, it will be pulled back in the other direction Simple harmonic motion

38. Surface waves Occur at boundaries between two different medium Combination of the two Particles in the medium roll or take a circular path Example: Ocean waves, Surface wave of an earthquake

39. What are the types of waves that do not need a medium to move ?

40. ELECTROMAGNETIC WAVES

41. Electromagnetic waves Light travels through space which does not contain matter in all places An electromagnetic wave does not need a medium to pass through a space. Additional examples of electromagnetic waves, x- rays, microwaves, ultraviolet light, infrared radiation, gamma rays… More about these when we discuss light

42. Difference in waves Related to the different ways that energy is transferred. Mechanical waves require a mechanical force to transfer the energy (things bumping into each other) The energy from Electromagnetic waves is absorbed by a atom and then readmitted

43. Difference in speed Electromagnetic are much faster As the medium gets denser, mechanical waves tend to get faster, electromagnetic waves tend to slow down