# Waves, Sound and Light: Sound and Music

## Sound and Music: Audio Guided Solutions

#### Problem 15:

Olivia and Mason are doing a lab which involves stretching an elastic cord between two poles which are 98 cm apart. They use a mechanical oscillator to force the cord to vibrate with the third harmonic wave pattern when the frequency is 84 Hz. Determine the speed of vibrations within the elastic cord.

## 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.