added the speed of light

1 files changed, 1 insertions, 1 deletions

diff --git a/Problem Set 3.page b/Problem Set 3.page
index 0090176..9045fa9 100644
--- a/Problem Set 3.page
+++ b/Problem Set 3.page
@@ -23,7 +23,7 @@ $$ \tau \frac{\partial u}{\partial t} - \lambda^2 \frac{\partial^2 u}{\partial x
 Use Fourier series to solve this equation in the case of a circular wire.  How does the solution depend on the magnitudes of the positive constants $\kappa$ and $\tau$?  
 
 6. The wave equation is a partial differential equation that models the propogation of disturbances in a medium (for example, the vibrations of a metal object that has been struck by a hammer).  In the case of a one-dimensional object it is given by:
-$$ \frac{\partial^2 u}{\partial t^2} = \frac{\partial^2 u}{\partial x^2} $$
+$$ \frac{\partial^2 u}{\partial t^2} = c^2 \frac{\partial^2 u}{\partial x^2} $$
 Use Fourier series to solve the wave equation in the case of a vibrating ring.  Interpret the solution as a superposition of two waves travelling with a certain velocity around the ring (but in opposite directions).  At what velocity do they travel?
 
 7. Write the Cauchy-Riemann equations in polar coordinates, i.e. express them as a relationship between $\frac{\partial f}{\partial r}$ and $\frac{\partial f}{\partial \theta}$.