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Homework

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  1. AIM: How do we determine which factors affect the period of a pendulum? Do Now: Draw a diagram of a pendulum and list what you could change about it. Homework Finish lab!

  2. Properties of a Pendulum • What are three things you can change about an pendulum? • What would be the period of a pendulum? • How could you test if each of these factors affect the period of a pendulum? • http://www.youtube.com/watch?v=r2gnD5NEplY

  3. Lab Goal: which factors affect the period of a pendulum? • Groups 1, 2: • Does mass affect the period of a pendulum? • Groups 3, 4: • Does length affect the period of a pendulum? • Groups 5, 6, 7: • Does release height affect the period f a pendulum?

  4. Lab Write-up • Goals (all 3) • Background: • What is a pendulum? • What is period? • Predictions: • Which of the factors will effect the period of a pendulum? • Procedures: • Mass • Length • Initial height • Data/Analysis: • Conclusion:

  5. AIM: What is a wave and how do we describe them? Do Now: Draw a wave and label any part of the wave you know. Homework Blue book pg 153-155 #1-47

  6. Simple Harmonic Oscillators • An object in simple harmonic motion experiences a net force which obeys Hooke’s Law • The oscillator oscillates about an equilibrium position (or mean position) between two extreme positions of maximum displacement in a periodic manner • Periodic means regular (same every time) and repeating Mass on a spring pendulum

  7. Parameters and parts of waves

  8. Vocabulary • Period (T): • The time for one oscillation • Measured in Seconds • Period = Time/number of oscillations • Frequency (f) • The number of oscillations in one second • Measured in Hertz; Hz (1/s or s-1) • Frequency = Number of oscillations/time • Mathematical Relationship between Period and Frequency • Period and frequency are inversely related

  9. Examples • A mass on a spring completes 10 oscillations in 30 seconds. • What is the period of oscillation? • What is the frequency of oscillation? • A pendulum completes 5 swings in a minute • What is the frequency of oscillation? • What is the period of oscillation?

  10. Waves • Waves are repetitive disturbances that transfer ENERGY without transferring MATTER • energy transferred without matter being transfered • Mechanical Waves require a medium to travel through. • Mediums include; water, air, anything solid • SOUND is a mechanical wave • "the wave" • Electromagnetic Waves do not require a medium to travel through. They can travel through a vacuum (empty space) • Empty space exists outside of Earth’s atmosphere • LIGHT, Xrays, Radio Waves are all examples of electromagnetic waves • electromagnetic waves

  11. The Electromagnetic Spectrum • ALL electromagnetic waves travel at the speed of light! • cis the symbol for the constant “speed of light” • cis always equal to 3x108 m/s when electromagnetic waves are traveling through a vacuum. • This speed can be decreased by sending light through a different medium • Nothing can ever travel faster than the speed of light. • Visible light is the same type of wave as a radio wave, an Xray, or a microwave. Its just a different size! • electromagnetic spectrum

  12. Visible Spectrum. Each color is within these FREQUENCY ranges. Remember, higher frequency, lower wavelength The Electromagnetic Spectrum VERY small wavelengths VERY high frequencies VERY low frequencies VERY high wavelengths

  13. The Electromagnetic Spectrum Gigahertz Megahertz Nanometers Kilometers meters

  14. Two Classes of Waves Transverse Waves Longitudinal Waves The particles vibrate in a direction that is parallel to the waves propagation (aka compression waves) The particles vibrate in a direction that is perpendicular to the waves propagation (direction of travel)

  15. Parts of a Wave Crest: the top-most part of a wave Amplitude: the distance from the equilibrium line to the crest or to the trough (measure in meters) Wavelength (λ): the distance between two similar points on a wave (measured in meters) Trough: the bottom-most part of a wave

  16. Wave Pulse One single Vibration or disturbance - The amplitude of SOUND ONLY tells you about the energy in the wave Longitudinal Pulse • Transverse Pulse One Crest Or One Trough One rarefaction Or One compression

  17. Phase • The relative position between… • Two different points on the same wave • Phase is measured in degrees and follows the conventions of a sine curve. 90o One-quarter wavelength 180o Half wavelength 360o One fullwavelength Reference Point 0o 270o three-quarter wavelength

  18. Phase • The relative position between… • Two similar points on different waves • Pick the same point on each wave and look at the difference between their relative positions 90o out of phase, 1/4 wave apart 180o out of phase, 1/2 wave apart 270o out of phase, 3/4 wave apart 360o out of phase, AKA IN PHASE 1 full wavelength apart

  19. AIM: What affects the speed of a wave? How do we calculate a wave’s speed Homework Finish 1-47 in the blue book. Questions are posted on the website QUIZ ON THEM TOMORROW! Do NOW! Make a compare and contrast list of everything you know about sound waves and light waves

  20. Sound Waves vs. Light Waves Sound Waves Light Waves Electromagnetic wave Transverse wave Amplitude tells you about intensity/brightness Frequency tells you about type of wave/color The speed of light in air is 3x108m/s Light slows down in solids • Mechanical Wave • Longitudinal wave • Amplitude tells you about volume • Frequency tells you about pitch • The speed of sound in air is about 330m/s • Sound travels faster in most solids than it does in air

  21. Recall… • You are standing on a dock and observe 15 waves pass you in 1 minute. • What is the frequency of the waves? • What is the period of the wave? • What is the difference between a mechanical and electromagnetic wave? • What is the difference between a transverse and longitudinal wave?

  22. standing wave • A wave that appears to be “standing still” and not moving either left or right. • - Particles seem to vibrate up and down • In order to create a standing wave, you need • - Two waves, moving in opposite directions, with the same amplitude and frequency Antinodes: points that move the most Nodes: points that don’t move

  23. Measuring Parameters of a Wave • Goal: we are going to use a standing waveto measure and investigate the affect of the amplitude, frequency, period, and wavelengthon the speedof a transverse wave. • Prediction: Which of the four parameters do you think will affect the speed of the wave and why. • Background: in a paragraph, please define all bolded words above. • Diagram: Draw a diagram of a transverse wave and label all the parts of the wave. • Materials • Slinky, stopwatch, meter stick

  24. Procedure • Measure 4m length across the floor and a 0.5m and 1m amplitude. • Have one person hold one end of the slinky still while having the other person generate a half wavelength standing wave with a 0.5m amplitude • Have 10 classmates time 20 complete oscillations of the wave. • Calculate the period, frequency and wave length for this trail and enter the numbers into the data table. • Repeat for a 1m amplitude then for 1 wave, 1.5 waves, 2 waves, 2.5 waves and possibly 3 waves. • Using the data table, try to determine how you would calculate the speed of the wave. • Once the speed for each wave is calculated, determine which parameters affect the speed of the wave and which don’t.

  25. Data

  26. Data

  27. Analysis • Show a sample calculation for each of the following • Period of the wave • Frequency of the wave • Speed of the wave. • What formula did you come up with to calculate this? (hint: use the units!) • Percent difference between velocities. • Do they appear different? • Conclusion • Restate goal • What is the formula for the speed of the wave? • What parameters affect the speed, which don’t? • If the frequency was changed, did the speed or the wavelength change? • How could you change the speed of this wave? • Sources of error/one future experiment

  28. Calculating the speed of a wave • A 5m long wave passes the end of a dock once every 10 seconds. • What is the period of the wave? • What is the speed of the wave? • A light wave has a frequency of 6MHz • What is the frequency in Hertz? • What is the speed of the wave? • What is the wavelength of the light? • What type of light wave is this?

  29. Do Now WORKING ON YOUR OWN, complete the crossword. You can use your notes. You have 7 minutes from the beginning of the period. If you finish, take out the lab we worked on yesterday and finish writing the background and write a conclusion paragraph • Conclusion • Restate goal • What is the formula for the speed of the wave? • What parameters affect the speed, which don’t? • If the frequency was changed, did the speed or the wavelength change? • How could you change the speed of this wave? • Sources of error/one future experiment

  30. AIM: What is Reflection? http://www.youtube.com/watch?v=kVzTWDwQzrc&feature=related Do Now: Describe what you heard and explain it in terms of reflection Homework Castle Learning Assignment due Monday!

  31. Wave Behaviors

  32. 3 Options The transmission of the lights on the inside of the building • When a wave hits a boundary, it does a combination of 3 things • Reflection • Bounces off the boundary • Absorption • Gets absorbed and turned into heat • Transmission • Goes through the boundary The reflection of the lights coming off the car on the outside of the building

  33. Law of ReflectionHow to draw the diagram • The Law of Reflection states • Angle of incidence is equal to the angle of reflection Normal Line: A reference line always drawn perpendicular to the surface USE A PROTRACTOR!!!! Reflected Ray: The light ray on the way AWAY FROM the surface Incidence Ray: The light ray on the way INTO the surface ϴi ϴr Angle of incidence ϴi: angle made between the incident ray and the normal line Angle of Reflection ϴr: angle made between the reflected ray and the normal line

  34. Reflection of Light • The bouncing of a wave off of a surface . • Regular reflection • Bouncing off of a Smooth surface • Mirrors, ponds • You can see an image of the object • Diffuse Reflection • Bouncing off of a Rough surface • The road, leaves, furniture, cloths • You can see light, but no image

  35. Reflection of sound • The bouncing of a wave off of a surface. • Regular reflection • Bouncing off of a Smooth surface • ECHOs If the speed of sound in water is 1.5Km/s and the signal takes 0.8 seconds to come back to the boat, HOW DEEP IS THE WATER?

  36. Echos A person in the grand canyon screams and hears the sound come back to her 1.2 seconds later. How far away is the other face of the canyon?

  37. Reflection Ray Diagram Object Distance Image Distance Object Image Appears where the virtual rays cross Reflected Angle Incident Rays Reflected Ray Incident Angle Eye sees two diverging rays and traces them back Normal Line • Law of Reflection in a PLANE mirror: • Object distance (do) is equal to image distance (di) Mirror

  38. Reflection Lab Goals: • To draw a 2-ray diagram of a single pin image • Use this diagram to compare the incident angles to the reflected angle - Use percent difference to determine if the object distance is the same as the image distance • Use this diagram to compare image distance to object distance • Use percent difference to determine if the object distance is the same as the image distance

  39. 1. Draw a line down the middle of the page, perpendicular to the edge of the page

  40. 2. Prop the mirror up against the book with the BACK surface of the mirror on your mirror line. Make sure the cardboard is under the paper

  41. 3. Stick the pin in the middle of the page

  42. 4. Look in the mirror from the angle and locate the image of the pin in the mirror Image of the pin