Consider the general solution to the wave equation, namely Y(x, t) = f(x - vt) + g(x + vt). If an infinitely long string is pulled into the shape of some function, say ϕ(x) and then released from this position with no initial velocity at each point, the initial conditions are Y(x, 0) = ϕ(x) and ∂Y/∂t(x, 0) = 0. Calculate ∂Y/∂t(x, t) and substitute these initial conditions to show that Y(x, t) = 1/2 ϕ(x - vt) + 1/2 ϕ(x + vt), which means that the resulting wave consists of two parts with the same shape as the initial distortion (but each having half the amplitude) travelling in opposite directions with the same speed away from the distorted area.