Answer
1.3 m/s
Work Step by Step
There is an antinode at each side of the tub, and a node right in the middle. Looking at figure 11-41b, we see that successive antinodes are a half-wavelength apart, i.e., the wavelength is twice the tub length.
The wave speed is given by $v=\lambda f$.
The frequency is $0.85 Hz$. The wavelength is 1.5 m.
Solve for $v=\lambda f \approx 1.3 m/s$.
