Let's return to our previous sample problem, with a wave on a string given by:

y(x,t) = (0.9 cm) sin[(1.2 m^-1)x - (5.0 s^-1)t]

The mass/unit length of the string is μ = 0.012 kg/m, and we determined that:

v = 4.17 m/s

What is the average power transmitted by the wave?

P_avg = ½ μ ω ² A² v

P_avg = ½ (0.012) (4.17) (5.0)² (0.009)² = 5.1 x 10^-5 W