partial differential equations (graduate)
Posted: Wed May 04, 2022 10:57 am
partial differential equations (graduate)
Q2) Let u be a smooth solution of the wave equation, which is L- periodic with respect to the space variable, that is u is a solution of the problem UttUxx=0, x ER, t > 0, - under the condition u(x, t) = u(x + L, t), x = R, t> 0. Show that 1 [⁄u²(x, t) + —⁄u²(x, t) + 3⁄u²(x, t)u²(x, t)]dx is constant.
Q2) Let u be a smooth solution of the wave equation, which is L- periodic with respect to the space variable, that is u is a solution of the problem UttUxx=0, x ER, t > 0, - under the condition u(x, t) = u(x + L, t), x = R, t> 0. Show that 1 [⁄u²(x, t) + —⁄u²(x, t) + 3⁄u²(x, t)u²(x, t)]dx is constant.