Step 1: Understanding the Question:
The given equation represents a transverse wave. We need to find the relationship for wavelength \( \lambda \) when the maximum particle velocity of the medium is four times the propagation velocity of the wave.
Step 2: Key Formula or Approach:
1. Standard wave equation:
\[ y = y_0 \sin(\omega t - kx) = y_0 \sin \left(2\pi f t - \frac{2\pi}{\lambda} x\right) \]
where \( y_0 \) is the amplitude, \( \omega = 2\pi f \) is the angular frequency, and \( k = \frac{2\pi}{\lambda} \) is the wave number.
2. Maximum particle velocity (\( v_{p,\text{max}} \)):
\[ v_{p,\text{max}} = A \omega = y_0 (2\pi f) \]
3. Wave velocity (\( v_w \)):
\[ v_w = f \lambda \]
Step 3: Detailed Explanation:
According to the given condition:
\[ v_{p,\text{max}} = 4 v_w \]
Substitute the expressions for \( v_{p,\text{max}} \) and \( v_w \):
\[ y_0 (2\pi f) = 4 (f \lambda) \]
Since frequency \( f \) is non-zero, we can cancel it from both sides:
\[ 2\pi y_0 = 4 \lambda \]
Solve for the wavelength \( \lambda \):
\[ \lambda = \frac{2\pi y_0}{4} = \frac{\pi y_0}{2} \]
Step 4: Final Answer:
The wavelength is \( \lambda = \frac{\pi y_0}{2} \).