Hey guys,

i have a small question. 1D-Wave equation is given as:

$\displaystyle

\frac{\partial^2 u}{\partial t^2}=\frac{\partial^2 u}{\partial x^2} $

i need to find $\displaystyle u_s(x,t)=X(x)sinwt$

From the equation form above , U_xx=$\displaystyle X''(x)sinwt$

U_tt=$\displaystyle -w^2X(x)sinwt$ are obtained as given as a solution.

My question is how $\displaystyle -w^2$ is obtained from $\displaystyle u_s(x,t)=X(x)sinwt$

thank you,