Practice question

**Beat formation** is interference in time with time-varying amplitude. Frequencies close together generate slow modulation, count in given duration obtained by multiplying beat frequency by duration, e.g., 6 Hz × 5 s = 30 beats. μ = (0.025/2.5) = 0.01 kg/m . v₁ = (v/2L) ⇒ 40 = (v/2 × 2.5) ⇒ v = 40 × 5 = 200 m/s . v = √((T/μ)) ⇒ 200 = √((T/0.01)) ⇒ 200² = (T/0.01) . T = 40000 × 0.01 = 400 N . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 400 N, illustrating frequency-length-speed interdependence and quantization by boundaries.