LESSON: Speed of Mechanical Waves

LESSON: Speed of Mechanical Waves

AS we discussed last week, wave velocity, wavelength and frequency are all related.  In fact, wave velocity = wavelength x frequency.  In equation form, that is

v = λf

The unit for velocity is m/s, the SI unit for wavelength is meters, and the SI unit for frequency is Hertz, sometimes written as 1/s or s^-1.

In a given medium, wave speed is constant.  For example, ALL mechanical waves travel through room-temperature steel at 6100 m/s.  All mechanical waves travel through room-temperature air at 343 m/s.  Waves travel faster through denser materials, so there are a few things to consider

1. The type of material (wood, metal, cotton candy...): Denser materials allow waves to travel faster.

2. The state of matter (solid, liquid, gas): Waves travel fastest through solids and slowest through gases.  This is because the molecules are most tightly packed in solids, so they can easily transfer the energy of waves between molecules.

3. The temperature of the material: Higher temperature materials have faster moving molecules, which allow waves to travel faster.

After you have completed this part of the lesson, you can check the associated box on the main course page to mark it as complete