Practice question

**Interference of waves** produces enhancement or cancellation based on phase. Two equal amplitude waves out of phase by π cancel completely, A = 0, while in-phase superposition doubles amplitude to 2a, demonstrating energy redistribution without violation of conservation. ω = 2π v = 2π × 40 = 80π rad/s . Max speed: vₘₐₓ = a ω = 0.015 × 80π ≈ 3.77 m/s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 3.8 m/s, illustrating frequency-length-speed interdependence and quantization by boundaries.