Waves, Sound and Light: Sound and Music

Sound and Music: Audio Guided Solutions

Problem 7:

The intensity of sound waves decreases as the distance from the source of sound increases. The relationship between intensity (I) and distance (d) is an inverse square relationship which follows the equation I = P/(4•π•R2) where P is the power of the sound source, usually expressed in Watts. Jake recently purchased a stereo system for his basement recreation room. Determine the maximum intensity of the sound waves at the following distances from his 120-Watt main speaker.
a. 1.0 meter
b. 2.0 meter
c. 3.0 meter

Audio Guided Solution

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Habits of an Effective Problem Solver

  • Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
  • Identify the known and unknown quantities and record in an organized manner, often times they can be recorded on the diagram itself. Equate given values to the symbols used to represent the corresponding quantity (e.g., v = 345 m/s, λ = 1.28 m, f = ???).
  • Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
  • Identify the appropriate formula(s) to use.
  • Perform substitutions and algebraic manipulations in order to solve for the unknown quantity.

Read About It!

Get more information on the topic of Sound and Music at The Physics Classroom Tutorial.

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