# Wave Equation Word Problem

• May 5th 2011, 12:28 PM
mathematicalbagpiper
Wave Equation Word Problem
At time $t=0$, two explosions occur in 3-space. They are contained within the spheres of radius 1 at the points (4,0,0) and (0,9,0). If you are located at hte point (0,5,0), what is the largest set of times $t>0$ for which you will not hear sounds from either explosion?

OK, so this is a 3-D wave problem, I know that, and I could probably solve it pretty easily. However, I'm having trouble with the setup. Can someone point me im the right direction as far as the setup is concerned?
• May 5th 2011, 03:27 PM
TKHunny
Quote:

Originally Posted by mathematicalbagpiper
I could probably solve it pretty easily. However, I'm having trouble with the setup.

I'm always humored by this description. It's the "setup" that's important!

First Question: Does it need to be 3D? Only three locations.
• May 5th 2011, 03:39 PM
mathematicalbagpiper
Well, seeing as how we're at the particular points in space, and z=0 at all of them, I suppose this could reduce down to 2D.
• May 5th 2011, 06:08 PM
TKHunny
Note: With only 3 locations, this would ALWAYS be the case.

Okay, now the sources. Can we use point sources or are we "1" closer than that?