Correct answer: 3.6
The wave equation is y = 60 cos(180t − 6x). The maximum particle velocity is given by ωA, where ω = 180 rad/s and A = 60 × 10⁻⁶ m. Thus, maximum particle velocity = 180 × 60 × 10⁻⁶ = 10.8 × 10⁻³ m/s. The wave velocity is v = ω/k = 180/6 = 30 m/s. The ratio of maximum particle velocity to wave velocity is (10.8 × 10⁻³) / 30 = 3.6 × 10⁻⁴. Hence, the correct answer is A) 3.6.