Solution
Robert answered on
Dec 26 2021
Ans. 1
So the given initial boundary problem,
2 0 1
( ,0) (1 )
( ,0) 0 0 1
(0, ) (1, ) 0 0
tt xx
t
u C u x
u x x x
u x x
u t u t t
So, we use separation of the variable,
Let,
( , ) ( ) ( )u x t X x T t
2
2
2
2
2 2
1 1
dT d X
X c T
dt dx
dT d X
dt Xc T dx
Separating the boundary conditions:
(0, ) 0 (0) ( ) 0 (0) 0
( , ) 0 ( ) ( ) 0 ( ) 0
x
dX dX
u t T t
dx dx
u L t X L T t X L
Now, the solution toeigon valueproblem is,
2
(2 1) (2 1)
, ( ) cos , 1,2,...
2 2
n n
n n x
X x n
L L
And,
2
2 2 1
2
( )
n
c t
L
n nT t c e
Now, for n
2
2 (2 1)
2 (2 1)( , ) cos
2
n
c t
L
n n
n x
u x t c e
L
Or,
2
2 (2 1)
2
1
(2 1)
( , ) cos
2
n
c t
L
n n
n
n x
u x t c e
L
Now, to solve the initial value constant apply the boundary conditions,
2
2 (2 1)
2
1
(2 1)
( ) ( ,0) ( , ) cos
2
n
c t
L
n n
n
n x
f x u x u x t c e
L
So from earlier, the section
(2 1)
cos
2
n x
L
is lie in a orthogonalsection 0 1x
So,
0
2 (2 1)
( )cos
2
L
n
n x
c f x dx
L L
...