At $t=0$ s, a small "upward" (positive $y$ ) pulse centered at $x=6.0 \mathrm{m}$ is moving to the right on a string with fixed ends at $x=0.0 \mathrm{m}$ and $x=10.0 \mathrm{m} .$ The wave speed on the string is $4.0 \mathrm{m} / \mathrm{s}$. At what time will the string next have the same appearance that it did at $t=0$ s?