Quiz 2 Prep: Steady state heat flow

The left end of bar of length 2 is held at the constant temperature $T=3$ while the right side is insulated.

  1. Write down the boundary value problem as an ODE and pair of boundary conditions that describes this situation mathematically.
  2. Solve your boundary value problem and show that it agrees with our physical understanding.

Comments

  • I'm having a really hard time setting this one up....

  • same, and the only class recording available is from august 24th. Even googling hasn't really helped.

  • edited September 2020

    Not totally confident but I think we have:
    $u(0)=3,$ $u'(2)=0$ and $u''=0.$

    So $$u''=0 \rightarrow u'=a \rightarrow u=ax+b.$$

    Using boundary conditions:
    $$u(0)=3=a(0)+b \rightarrow b=3$$
    and
    $$u'(2)=0=a.$$
    Thus
    $$u(x)=3.$$

    I chose $u'(2)=0$ because the right side of the bar is insulated. Which implies there is no change in temperature across that boundary. So I interpret this situation to mean that after the bar reaches steady-state, the temp is constant across the bar.

    mark
  • maxmax
    edited September 2020

    This is what I got... Using 317 of the textbook.
    But as Stephen said, it should be $u'(2)=0$

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