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What Are Some Properties of Waves Unit E, Chapter 4, Section 1 pE108-113.

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Presentation on theme: "What Are Some Properties of Waves Unit E, Chapter 4, Section 1 pE108-113."— Presentation transcript:

1 What Are Some Properties of Waves Unit E, Chapter 4, Section 1 pE

2 Waves Wave: disturbance that travels through matter or space, carrying energy from one place to another without carrying matter with it – Information we receive travels in waves Light, sound, radio, televisions, – Mechanical waves: waves that need matter to travel through Substance, matter, only vibrates back & forth or side-to-side Floating object – Bobs up and down – Doesnt move in direction of waves – Waves dont transport matter, they only transport energy

3 Waves Surface waves in water = combination of motion of two kinds of waves – Back and forth vibration – Side-to-side vibration – Resulting motion is circular

4 Waves Crest: highest part of wave Trough: lowest part of wave Height: vertical distance between crest and trough Amplitude: distance any point on wave is moved from resting position – Equal to ½ height – Greater energy of wave, greater amplitude – Measured from resting position to crest or trough

5 Waves Wavelength: horizontal distance between one crest and the next – Always the same in a series of waves – Can be measured between any two identical points Amplitude and wavelength of waves can vary greatly

6 Different Kinds of Waves Transverse wave: particles vibrate at right angles to direction of wave – Yarn moved side-to-side – Waves traveled forward Examples: – Guitar string – Light (Electromagnetic waves) » Light doesnt need a medium, matter, to travel through

7 Different Kinds of Waves Longitudinal wave: particles vibrate back and forth in the same direction as the wave is moving – Compressions: areas where particles are closer together – Rarefaction: areas where particles are spread out – Examples: Sound waves Most other waves that travel through liquids or gases

8 Speed, Frequency, and Wavelength The speed of a wave is always the same in a particular substance, unless there are changes to the substance – Speed of sound through air always the same Change temperature – speed changes – Speed of waves through water always the same Change depth – speed changes – Speed measured by measuring distance a single point, crest or compression, travels in given time

9 Speed, Frequency, and Wavelength Frequency: number of vibrations a wave has in a given time – Measured by counting number of crests or compressions passing point in certain amount of time – Measured in units called hertz 1 hertz = 1 vibration per second – 1 crest passes a point in 1 second 2 hertz = 2 crests passing in 1 second

10 Speed, Frequency, and Wavelength Relationship: – Speed = wavelength x frequency Increase frequency, wavelength decreases – Faster you sent waves down spring, shorter distance between waves

11 Energy From Waves All waves carry energy in the form of: light, sound, heat, or motion – Life on Earth depends on waves carrying energy from sun Heats planet Allowing plants to make food

12 Energy From Waves People use energy carried in waves – Solar panels Change suns light energy into heat or electricity – Ocean waves Scientists doing experiments to use energy Advantages: – Renewable source – Wont cause pollution from combution

13 Energy From Waves Energy in waves can also destroy – Hurricane waves Huge amounts of energy Cause almost as much damage as winds – Tsunami: waves generated by undersea earthquakes Tidal waves Carry greatest amount of energy – Begins on ocean floor – On surface it not very noticeable – When it reaches shore, height may be 35 m (115 ft)

14 Energy From Waves Energy in waves can also destroy – Earthquakes Seismic waves Energy travels through Earth – Both transverse and longitudinal – Third kind of wave on surface, similar to water » Ground ripples up and down » Circular motion

15 Summary Mechanical waves are disturbances in a substance that carry energy without carrying the substance (matter) Other waves, i.e. light, carry energy without needing matter to travel through Transverse waves displace particles at right angles to the motion of the wave Longitudinal waves displace particles in the same direction as the wave Relationship – speed = wavelength x frequency Some energy from waves can be used, but the energy in waves can also cause great damage

16 Homework Read Unit E, Chapter 4, Section 1, pE Answer ?s on Google Form or WS

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