# Maximum order of essential and natural conditions

1. Feb 7, 2015

### ENgez

Is there a physical explanation for why when given a differential equation with spatial derivative of spatial order $2m$ the maximum order of the essential (displacement) boundary condition is $m$, and the maximum order of the natural (force) boundary condition is $2m-1$

for example, the equaiton governing the dynamic behavior of a 1D bar is:
$\frac{\partial ^{2}u}{\partial x^2} = \frac{1}{c^2} \frac{\partial ^{2}u}{\partial t^2}$

the maximum order of the essential boundary condition is 0 :
$u(0,t)=0$
and the maximal order of the natural boundary condition is 1:
$EA\frac{\partial u}{\partial x}(L,t)=R(t)$

2. Feb 12, 2015

### Staff: Admin

Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?

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