akemiiwaya — 2014-08-11T13:30:01-04:00 — #1
Originally published at: http://www.howtogeek.com/194691/5-fun-physics-phenomena/
Do you enjoy trying to figure out how awesome physics tricks work? Then you will definitely have fun with today’s challenge! YouTube channel Veritasium presents five awesome physics tricks for you to figure out in today’s video.
wilsontp — 2014-08-11T14:30:17-04:00 — #2
The cane trick: when you move your fingers closer to the center of the cane, the finger that's further from the center of mass is supporting less weight, so it slides more easily.
Phone flipping: the phone's weight is not evenly distributed. When you flip it along the shorter two axes, the weight distribution is not as big an issue as when you flip it along the long axis; centripetal force causes the heavier parts of the phone to want to move outward, causing the phone to rotate.
Water that is carried through metal pipes will have the same electrical potential as the ground; since you've also charged the cup by rubbing it on your hair, he cup is also charged. This will cause the cup to repel or attract any electrically charged object - including the water molecules. It's not due to the water's polarization, but rather the overall ionization of the cup and water.
Cereal often has iron added; this is not part of the cereal itself, but is basically super-fine iron shavings. Total brand cereal is the best example of this: you can crush total and actually collect iron dust with a magnet.
The flame creates a vertically moving column of air. Once the bag gets down to the end, it's basically ash...this is the same reason ash and sparks fly up from a campfire.
as82 — 2014-08-12T19:11:01-04:00 — #3
The phone weight has nothing to do with it, as this trick would work with even a perfectly balanced phone. Air resistance is the key. The face has to travel through the air and because of the large exposed surface area it forces a lateral rotation.
wilsontp — 2014-08-12T19:34:04-04:00 — #4
Nope. I just tried it with an object with a uniform mass (a phone case, actually), and it doesn't do this. To test this consistently, I held the case at the edge of a table and let it fall off. The case spun perfectly evenly all the way down to the ground.
sirraf03 — 2014-08-12T19:37:49-04:00 — #5
I agree with @wilsontp on all but #2, but I think it's a combination of weight and air as @as82 suggested. For instance, the heaviest part of the phone is going to be the battery which in most phones will be off center, more towards one end of the phone so when you flip either of the two first directions it has it's own direction or assists (more or less) with rotation of the phone and the air resistance is negligible. But when you flip the phone from the final direction, the battery is at the end of the phone causing the rotation to try to center on it, and the air resistance is greater trying to force the phone to turn for less resistance.
wilsontp — 2014-08-12T19:46:07-04:00 — #6
Actually, in thinking about it, I think the problem is that when you flip the phone the long way, the length of the phone magnifies the imprecision in your toss, making it tend to move directions other than the way you expected it to go.
As I said, I tested this several times by letting the case fall off the edge of a table, and it flipped perfectly every time... but I couldn't toss it by hand and have it flip around evenly even once.
Other household items with an uneven distribution of mass do flip unevenly.
sirraf03 — 2014-08-13T20:52:48-04:00 — #7
OK, he did the answer video:
akemiiwaya — 2014-08-14T02:58:38-04:00 — #8
@sirraf03 - Thanks for posting the answers video link. ^_^
wilsontp — 2014-08-14T11:32:34-04:00 — #9
Wow. I knew salt water could be pushed by a magnet, but I didn't think you could do it with tap water. (This is where the "worm drive" from Hunt For Red October came from.)
Thanks, @sirraf03. I'm going to subscribe to this guy's channel.
system — 2014-08-21T13:57:56-04:00 — #10
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