This Week's Puzzle Solver

C4C Tom McCaleb
Tom, a repeat Puzzle Solver, is still from Tallahassee, Florida. A Math major and someone with proven physics puzzle-solving prowess, Tom is also a country music fan. He's looking forward to making time for the Wings of Blue.

Congratulations, Tom!
You're the 215H Puzzle Solver of the Week!
Tom was the first person to correctly answer this week's puzzle, "When Bobbing Met Sally."

Other correct answers were submitted by:

Matt Roles, Andy Malin, Benjamin Hale, Andy Royle, Brian Hoose, Dave Blair, Erich Kunrath, and David Heinitz.

Other solutions which earned partial credit were submitted by:

Laura Nealon, Michael Young, Chris Geisel, Randy Carlson, Drew Judkins, Jeremy Wimer, Tim Spaulding, Tim Wagner, David Adams, Pat Currie, Brian Beekman, Josh Weed, David Peñuela, and Brandon Tellez.

This Week's Puzzle Solution is brought to us by Erich Kunrath:

"From the waves created by the boat I was able to figure out the velocity at which waves propogate in the lake. Since the motor boat was 30m from shore and it took 30 seconds for the waves to reach shore, the waves traveled at 1 m/s. Since the waves are in a lake we do not have to worry about them reflecting because they lose all their energy as they wash up on the shore. I then found the wavelength of the waves created by the two kids attached to the moorings. Since v=wavelength/T, I found that the wavelength equals 2 m. (The period was 2 seconds since 15 waves were produced every 30 seconds).
The two kids can be treated as the sources and with Sally they can be said to be in a triangular pattern. We'll say Sally's older brother is at the right angle vertex of the triangle and her sister is at the point 15 meters away from the right angle. The path difference (brother to Sally vs sister to Sally)in the first case is 5 meters. (SQRT(20^2+15^2)-20). In this path difference the wave from the sister becomes out of phase by pi radians. This means that the wave from the brother is canceled by the wave from the sister and Sally lies still. Being the physics expert he was, the father saw his children's fun wasn't working, so he decided to secretly help them. By moving Sally out another 6m he changed the path difference. The path difference changed to Sqrt(26^2 + 15^2)-26 = 4.02. Two more waves were produced by the sister by the time they reached Sally. However the two sources now produced waves that were now in phase. At the point where Sally was relaxing in her red plastic boat the waves superimposed and the amplitude doubled. Sally now got a wild ride.

Conclusion: Sally's father is a tease."

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