Grade 10 physics
Mechanical Waves; Measuring the Speed of Sound
A mechanical wave transfers energy and momentum through an elastic medium while particles oscillate about equilibrium rather than travelling with the wave.
1. Core ideas and learning goals
- Wave speed equals wavelength times frequency, v = lambda f, with speed set mainly by properties of the medium.
- Longitudinal waves oscillate parallel to propagation, while transverse waves oscillate perpendicular to it.
- Sound in air is a longitudinal pressure wave and cannot propagate through a vacuum.
- A time-of-flight measurement gives speed from a known path divided by travel time; an echo uses a round-trip distance.
- Frequency is fixed by the source, while wavelength changes when the wave enters a medium with a different speed.
2. Physical model
A mechanical wave transfers energy and momentum through an elastic medium while particles oscillate about equilibrium rather than travelling with the wave.
A mechanical wave transfers energy and momentum through an elastic medium while particles oscillate about equilibrium rather than travelling with the wave. The model links observable changes with measurable physical quantities and conservation laws.
Before applying a relation, specify the reference frame, system boundary, initial state and approximations. The conclusion is valid only while those conditions are satisfied.