Answer
$\phi = 0.93~rad$
Work Step by Step
$y(x,t) = (5.0~cm)~sin(kx+\omega t+\phi)$
On the graph, we can see that $y(0,0) = 4.0~cm$
We can find two possibilities for $\phi$:
$y(x,t) = (5.0~cm)~sin(kx+\omega t+\phi)$
$y(0,0) = (5.0~cm)~sin(0+0+\phi) = 4.0~cm$
$sin(\phi) = 0.80$
$\phi = 0.93, 2.2$
At $t=0$, on the graph, as $x$ increases slightly more than zero, the value of $y$ increases.
Therefore, $\phi = 0.93~rad$
