9TH GRADE · MECHANICAL WAVES AND SOUND
Mechanical waves
Longitudinal and transverse waves, length, frequency and speed.
The entire theory of the lesson is collected here; you can read it without an account. In interactive mode, the same theory appears as cards, followed by questions. with checking the answer and task, and progress is saved.
Basic Concepts
Longitudinal and transverse waves
In a longitudinal wave, particles oscillate along the propagation, and in a transverse wave, they vibrate perpendicular to it.
The sound in a gas is longitudinal, and the wave on a stretched string is transverse in a simple way.
Mechanical wave
Propagation of vibrations and energy in an elastic medium without transfer of matter over long distances.
Particles of the medium oscillate around equilibrium, transmitting disturbance to their neighbors.
Wavelength
The distance between the nearest points that oscillate equally is equal to the path of the wave in one period.
The speed of the wave is determined by the medium, so when the frequency changes, the wavelength changes in inverse proportion.
Physical quantities
Wavelength
The distance a wave travels in one period.
Unit: meter ·
Wave speed
The speed of propagation of the oscillation phase in the medium.
Unit: meter per second ·
Lesson formulas
Wave speed
The speed of a wave is equal to the product of the wavelength and its frequency.
Related formulas
The same formulas in the reference, with symbols and units.
Tasks on the topic
Statements, answer options and the walkthrough.