User talk:Cheung Chun Ping

Dynamic Structural Analysis
$$t\over2^-5 =dx/dt$$ $$\frac{dy}{dx}$$ $$a\frac{\partial x}{\partial f}$$

$$\rho A\frac{\partial ^2u}{\partial t^2}+c\frac{\partial u}{\partial t}+ku = \frac{\partial}{\partial x}(EA\frac {\partial u}{\partial x})+\frac{\partial}{\partial y}(EA\frac {\partial u}{\partial y})+\frac{\partial}{\partial z}(EA\frac {\partial u}{\partial z})$$