Quote:
Originally Posted by CalTran
So you made your arms safer by instead introducing a pinch point that would destroy whatever appendage happens to get caught between them?
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There have not been issues with pinching. If there is a finger or a hand in the way, the distance between the two magnets is enough to significantly diminish the attractive force between the two magnets. As one of the drivers who sets it up on the field, I did have the magnets attempt to pull together with my hand between them before I managed to set up our drop away. It was about the same amount of force as a gentle handshake. The force gets much stronger as the magnets get closer to each other, and equally decreases as the distance increases (I believe at a rate proportional to the cube of the distance, if memory serves me correctly). By the time the distance is great enough to fit a finger or hand between the magnets, the force is weak enough to be a non-issue. Just don't try to be funny and put your earlobe between them or you'll get a good pinch.
EDIT: A little research on the University of Illinois website appears to show that the strength of two magnets acting upon each other will fall off proportionally with the distance to the fourth power (read the second answer given).
https://van.physics.illinois.edu/qa/listing.php?id=419
The reason the pin was attracted from a greater distance is because it's quite light. I would agree with previous posters that robots from other years carried greater risks in terms of danger. My team's robot from 2014 used four linear composite springs with 80 pounds of force each to propel the ball, and our 2013 robot climbed all the way to the third level of the tower. Both of those represent much greater potential for bodily harm than two properly managed magnets on our canburglar device to prevent it from breaking loose.