Problem 12
If a square plate has its faces and the edge \(y=0\) insulated, its edges \(x=0\) and \(x=a\) are kept at zero temperature and the fourth edge is ikept at temperature \(u\), then the boundary conditions for this problem are ____ .
Problem 20
In the equation \(\frac{\partial u}{\partial t}=\alpha^{2} \frac{\partial^{2} u}{\partial x^{2}}, \alpha^{2}\) represents ____ .
