1. Waves pg. 55

2. Objectives Investigate and analyze the characteristics of waves including: velocity, frequency, amplitude, and wavelength. Compare the characteristics and behaviors of transverse waves and longitudinal waves. Physics terms oscillation wave wavelength frequency amplitude transverse wave longitudinal wave

3. Oscillators An oscillator is a system with motion that repeats in cycles.

4. Drop a pebble on a pond on a calm day. As the pebble breaks the surface, the water oscillates up and down—in harmonic motion. Ripples form and spread out. An oscillation that travels is a wave. What is a wave?

5. A wave oscillates up and down over time at a given point in space. The wave’s oscillations extend in space at any instant in time. Waves in time and space

6. Click to open the interactive simulation. Exploring the ideas In Investigation 15 A you will explore the wave properties of amplitude, wavelength, and frequency. This investigation will let you actually see what these different characteristics mean when it comes to waves before we actually go over them. Be sure to answer the questions in your ppt. as you play with the simulation.

7. This simulation allows you to overlay a mathematical model of a wave on a plotted blue wave representing water. When you match the wave’s characteristics, your mathematical wave model will move with the blue wave. Part 1: Match a wave’s properties

8. 1.Open the simulation. You will create a model of a wave (red line) to match the blue waves. 2.Adjust amplitude and wavelength to match the blue wave. 3.Run and Pause the waves. Adjust the frequency until the bobbing red circle matches the bobbing of the floating ball. Part 1: Match a wave’s properties

9. a.Change the amplitude of your wave. What happens when you make the…. o Amplitude bigger? o Amplitude smaller? b.Change the wavelength of your wave. What happens when you make the…. o wavelength bigger? o wavelength smaller? c.Change the frequency of your wave. What happens when you make the…. o frequency bigger? o frequency smaller? Part 1 Simulation Analysis Questions Gets taller Gets shorter Gets wider Gets narrower/thinner Gets faster/get more waves Gets slower/get less waves

10. A The amplitude A of a wave is the maximum amount the wave rises or falls compared to its resting level. What do you think the units for amplitude are? Amplitude Meters (m)

11. The wavelength λ is the distance a wave travels before it begins to repeat itself. The wavelength can be measured from peak to peak, or trough to trough. Wavelength λ

12. Frequency The frequency f of a wave is a measure of how quickly it oscillates OR how many cycles are completed each second. Frequency f is measured in Hertz or Hz.

13. Frequency What is the frequency of these oscillators? 1.your heartbeat 2.a fan that rotates 360 times a minute 3.the vibration of a guitar string 1 – 2 beats per second, or 1 – 2 Hz 6 cycles per second, or 6 Hz 100 – 800 Hz

14. When a wave has a frequency of 10 Hz = 10 cycles/second, then 10 waves travel past a given point each second. What is the frequency of the wave shown below? Frequency 2 Hz

15. The frequency of a wave conveys information. the frequency of a light wave determines its color. the frequency of a sound wave determines its pitch Frequency remains the same even if the wave amplitude decreases as it spreads out. Frequency

16. Period A full cycle is one complete back and forth motion. The period is the time it takes to complete one full cycle. Period T is measured in seconds. T

17. Period What is the period of the following oscillators? 1.Earth in its rotation 2.your heartbeat 3.the minute hand on a clock 4.a classroom pendulum 1 day, or 24 hours, or 86,400 seconds about 1 second 1 hour typically 1-2 seconds

18. The speed of a wave depends on the type of wave and on its medium. Examples: speed of typical water waves: 5 m/s speed of sound in air: 343 m/s speed of light: 300,000,000 m/s (in a vacuum) Wave speed

19. Equations Wave velocity equals the frequency multiplied by the wavelength. Wave velocity equals the wavelength divided by the period. Wave frequency equals 1 divided by the period. Solve for: Frequency: Wavelength: Solve for: Period: Wavelength: Solve for: Period:

20. 1.A water wave has a speed of 5.0 m/s and a wavelength of 2.0 m. What is its frequency? 2.What are two different ways you can get a wave speed equal to 100 m/s? 3.A sound wave has a speed of 343 m/s in air. What is the wavelength of a sound wave with frequency of 686 Hz? Math Practice 2.5 hertz λ =.5 m

21. Test your knowledge Two students use a 10-meter-long spring to create a standing wave. The wavelength is 2.0 m and the frequency is 2.0 Hz. How fast is the wave traveling along the spring? Given(s): Unknown: Equation: Sub: Solution: speed ( v)

22. Test your knowledge This wave’s motion is graphed as a function of time and distance. a.What is the wave frequency? b.What is the wavelength? c.What is the amplitude? d.Calculate the speed of the wave. 1 Hz 5 cm 10 cm 5 cm/s (0.05 m/s)

23. lower energyhigher energy low frequencyhigh frequency (slower oscillations)(faster oscillations) long wavelength short wavelength The energy of a wave increases with frequency: Energy and frequency

24. lower energy higher energy small amplitudelarge amplitude Energy and amplitude The energy of a wave also increases with amplitude:

25. 1.Determine the amplitude, period, frequency, wavelength & wave speed for the wave graphed below. Homework

26. 2. These graphs show the oscillation of a point on a wave as a function of time, and the oscillation of the extended wave in space at a moment in time. a.What is the frequency? b.What is the wavelength? c.What is the amplitude? d.Calculate the wave speed. 0.5 Hz 20 cm 0.5 cm 10 cm/s Homework