at time t$=0$ and at position x$=0$m along a string, a traveling sinusoidal wave with an angular frequency of $450$ rad$/$s has a displacement y$=+4\mathrm{.}5$mm and transverse velocity u$=-0\mathrm{.}76$m$/$s$.$ if the wave has the general form y$($x$,$t$)=$ymsin$($kx$-$wt$+)$ what is phase constant