What is the key requirement for a wave to be classified as a progressive wave?
**Mechanical waves** require medium and can be transverse or longitudinal. Sound in air is longitudinal since fluids support only compressional motion, while string waves are transverse. Progressive waves transfer energy without net mass transport, distinguishing from standing waves. A progressive wave transfers energy through the medium as it propagates, distinguishing it from standing waves, which do not exhibit net energy flow. Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields Energy transfer, illustrating frequency-length-speed interdependen
Ref: NCERT > Physics Book > Waves > Transverse and Longitudinal Waves