Waves and Sound

What are Waves?

Describe a Wave: Think about an ocean wave Think about an ocean wave –Now describe it

Waves Rhythmic disturbances that carry energy through matter or space Rhythmic disturbances that carry energy through matter or space –Ocean Waves – energy through water –Earthquakes – energy through Earth –Both travel through a medium Medium – a material through which a waves transfers energy Medium – a material through which a waves transfers energy

Two Types of Waves Transverse Waves – medium moves at right angles to the direction the wave travels Transverse Waves – medium moves at right angles to the direction the wave travels Compressional or Longitudinal Wave Compressional or Longitudinal Wave –A type of wave where matter vibrates in the same direction as the wave travels

Transverse Wave The wave is traveling in this direction  Rest Position

Amplitude Amplitude corresponds to the amount of energy carried by a wave Amplitude corresponds to the amount of energy carried by a wave –Large amplitude = Large amount of energy –Small amplitude = Small amount of energy

Wave Frequency The number of wave crests that pass one place each second. –E–E–E–Expressed in Hertz (Hz) One hertz = One wave per second –H–H–H–How do you increase the wave frequency? Rope demonstration –W–W–W–What happens to the wavelength when the frequency increases? TTTThe wavelength decreases!!!!! Meaning Increased wave frequency means decreased wavelength

Calculating Wave Frequency Velocity = Wavelength x Frequency Velocity = Wavelength x FrequencyOR V = λ x ƒ Example: A wave is generated in a wave pool at a water park. The wavelength is 3.2 m. The frequency of the wave is 0.60 Hz. What is the velocity of the wave? V = λ x ƒ V = ? λ = 3.2 m ƒ = 0.60 Hz V = 3.2 m x 0.60 V = 1.92 m/s Why m/s? Remember 1 Hz = 1 wave/second or m x 1/s or m/s