# Thread: Wave Equation Word Problem

1. ## 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?

2. 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.

3. 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.

4. 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?