1. The problem statement, all variables and given/known data Monochromatic transverse wave is propagating in the positive x direction on a string (neither end is fixed). The wave velocity is 12 m/s, amplitude 0.05 m, and wavelength is 0.4 m. At t=0 and x=0 the string altitude is 0, and moving in the positive y direction [i.e. (dy/dt)|(t=0) > 0] Find the altitude y at x=0.25 m and t=0.15 sec. 3. The attempt at a solution I figured that since y is 0 when x and t are 0, it must sine: y(x,t) = Asin(kx-ωt) I found the parameters I need: k = (2π/λ)=(2π)/(0.4) = 5π ω = vk = 12*5π = 60π and I get y(x,t) = 0.05sin(5πx-60πt) I plug in the values x=0.25 and t=0.15 and get y(0.25,0.15) = -0.02 But this is not the answer. Why? What did I do wrong?