PDE:Mathematical Modeling

Mathematical Modeling

solution Let the temperature $u\,$ inside a solid sphere be a function only of radial distance $r\,$ from the center and time $t\,$. Show that the equation for heat diffusion is now $u_{t}=\nu (u_{{rr}}+2u_{r}/r)\,$.

solution A ball is thrown straight up from the ground. How high will it go?