Given: Amplitude, $A = 2 \text{ cm} = 0.02 \text{ m}$ Velocity of wave, $v = 128 \text{ m/s}$ $5$ complete waves fit in a $4 \text{ m}$ length. Therefore, the wavelength $\lambda$ is: $\lambda = \frac{4}{5} = 0.8 \text{ m}$ The wave number $k$ is calculated as: $k = \frac{2\pi}{\lambda} = \frac{2 \times 3.14}{0.8} = 7.85 \text{ m}^{-1}$ The angular frequency $\omega$ is calculated using the relation $v = \frac{\omega}{k}$: $\omega = v \times k = 128 \times 7.85 = 1004.8 \approx 1005 \text{ rad/s}$ Since the wave is traveling in the positive x-direction, the general equation of the wave is of the form: $y = A \sin(kx - \omega t)$ Substituting the derived values: $y = (0.02 \text{ m}) \sin(7.85x - 1005t)$