Team Mertz's Ball Drop

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Team Mertz approached the problem of the ball drop from a completely different direction than the other teams; they built a cabled "descender", which would use a rope and frictional forces to slow their ball's descent instead of air resistance.

Group Members

The group members were:

Julian Leland

Pierre Dyer

Taylor Chen

Matt Bowers

John Dinh

Fritz Eyerer

Early Stages

Some of the ideas that came up early during Team Mertz's brainstorming session were felt to be uncreative, as well as seemingly complicated; among these were a parachute, a kite, and a glider.

With avoidance of a parachute-based design in mind, Team Mertz began considering friction-based descenders. These ideas largely centered around the use of the electrical tape as a cable which the tennis ball would "ride" to the ground; a number of ideas were proposed for how to slow the ball's descent, including wrapping the ball in the tape cord, applying friction to the cable with the lid and body of the tape container, and building a "counterweight"-based system.

After a prototype of the "counterweight" descender was demonstrated to work, the design was selected. The basic premise of the design was that forcing the ball to change direction in order to descend would slow its descent. The rate of descent could potentially be controlled by adjusting variables such as the wrapping pattern of the cord, the number of "arms" for the cable to wrap around (see final design for explanation) and the angle of said "arms".

Final Design & Construction

First, Team Mertz punctured the tennis ball and drove two dowels through, in such a way that they made an “X.” Then, they folded almost the whole length of the tape across the middle of the sticky side, producing roughly thirty feet of non-sticky tape. They then wrapped the tape in a figure of 8 around the two longest protruding legs of the “X.” Finally, they attached the end of the tape to the third dowel, so that they could use the dowel to hold the device as far from the building as possible when it was falling.



Team Mertz's descender achieved a time of 15.44 ± 0.2 seconds. Pretty sweet, eh?

(Side note: They also ran one test from the roof of Hicks in which they achieved a time of 55 SECONDS. Again, pretty sweet, eh?)


When we wrapped the tape around the dowels, we used a single wrap because we were concerned about snags. In hindsight, we could have used a double wrap to make our apparatus descend even slower.

Our design seemed to have irritated some of our competitors; indeed, a number of them believe that our project had broken some design rules. To quote the rules: "Use the material provided to design an apparatus to maximize the length of time the tennis ball will stay in the air when it is released from rest from the roof of Hicks (the ball must fall, you can't simply tape it to the building). The time must be less than 1 minute. No chemical reactions (i.e. fire) can be used." First of all, we clearly did not employ any chemical reactions. Second, our project descended well within the 1 minute time limit. Finally, we released the tennis ball allowing it to fall to the ground from the third floor window. Our project abided by all of the design rules, so in response to our competitors sour grapes we say, "thatll teach u to stay inside the box."

It must be recognized that we did employ a vastly different general paradigm than any of the other teams; in light of this, it may be fair to question whether or not our descender should be judged in the same "league" as the others. However, the challenge was ultimately to slow the ball's descent as much as possible, not to build the best air-resistance-based descender. Engineering requires exploration of all possible avenues in the search for a problem's solution. We found an avenue that was not only valid but unique and moreover effective; as such, we stand by our design.