A "Shocking" Boat Day
Thalia Levee
Award: Top 100
School: sleepy hollow high school
Teacher: leila madani
Category: Natural
Photo #21084
A "Shocking" Boat Day
When my friends suggested a boat day on the Hudson River, I expected peace and rejuvenation. However, when they proposed tubing, my dreams of a calm afternoon vanished. I already knew what the "fun activity" entailed: a flimsy raft violently tugged by a motorboat, with a driver set on creating chaos.
As shown in the image I took on my iPhone, tubing demonstrates the physics concepts of constructive interference and the Doppler Effect. The motorboat generates waves spreading outwards. Since the boat travels faster than the waves it produces, a cone-shaped shock wave pattern is produced behind the boat. When the crest of one shockwave combines with the crest of another, constructive interference occurs, resulting in one higher-amplitude wave. The driver's reckless twists and turns cause the raft to cross this path of constructive interference, now causing it to launch into the air and come crashing down.
Newton's Law of Inertia is behind the launch of the rafters. As the raft suddenly accelerates sideways (thanks to the motorboat driver's zigzags), the riders' inertia keeps them moving straight. This is what makes tubing so dangerous, or according to some, fun! Because the riders' inertia keeps their bodies moving in straight-line motion, they encounter the super-high shock wave crests, and they are violently ejected from the raft. If the boat kept driving straight, the riders would easily stay on board, riding in the calm part of the boat's wake. But where's the fun in that!?
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