Practice question

**Wave classification** depends on particle vibration relative to propagation. Longitudinal waves have particle oscillation parallel to propagation, creating compressions and rarefactions as in sound in air; transverse have perpendicular oscillation. Tuning fork generates longitudinal sound because air cannot sustain shear. ω = 2π v = 2π × 20 = 40π rad/s . Max speed: vₘₐₓ = a ω = 0.035 × 40π ≈ 4.4 m/s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 4.4 m/s, illustrating frequency-length-speed interdependence and quantization by boundaries.