Properties and Detection of Sound

1. State that sound waves are a longitudinal pressure wave.
2. State that the speed of sound depends on the medium it is transmitted through.

   high density: slows a wave down because the media the wave passes through has more inertia

   high stiffness ( force/deformation): speeds a wave up

   Media	Stiffness (bulk modulus of elasticity, N/m^2)	Density (kg/m^2)	Speed of Sound (m/s)
   air	5 (10^4)	1.2	340
   water	2 (10^9)	1000	1500
   steel	2 (10^11)	7850	6100

    

3. Explain why the wavelength of a sound is altered when it is transmitted through different media because the frequency is not. Since frequency (number of peaks per second) is constant, wave length is directly proportional to the speed of sound in a material as shown:

   l = (1/f) v

   where f = a constant

4. Explain the difference between hearing by bone transmitted sound vs. air transmitted sound.
5. Explain why a noise transmitted in water sounds different (somewhat lower pitched) than the same noise transmitted in air. The wavelength of a sound traveling in water will be longer than a wavelength traveling in air.
6. Explain why audible sound could not be transmitted through outer space. (see Stokes' law of sound attenuation.)

   extreme low density of space: While there is some matter in outerspace, the density is near zero causing sound to be almost instantly attenuated (reduced to essentially zero loudness)

   extremely low frequency mechanical waves are attenuated less: these extremely low frequency waves can travel longer distances but are far below human hearing levels.

7. Solve problems using the speed of sound. v = l f

   given any two of the quantities v, l, or f solve for the third

    

Homefun (formative/summative assessment): Read sections 14.1, practice problems 1, 3, 5 page 405

Formative Assessment: Physics Investigation

Follow up Questions

 

Perceiving Sound

8. S

Homefun (formative/summative assessment) .

Sn

19. D

     

Homefun (formative/summative assessment):

Review

Formative Assessments:

1. Work review problems at the board

2. Work practice problems.

Metacognition Problem Solving Question: Can I still work the problems done in class, several hours or days later? Some amount of repetition on the exact same problems is necessary to lock in learning. It is often better to thoroughly understand a single example of a problem type than to work example after example understanding none of them completely.

Relevance: Good test preparation is essential to performance in physics class.

Homefun (formative/summative assessment): turn in on the day stapled to the back of the test.

Summative Assessment: Unit exam objectives 1-23