just when i think i've lost my students to the somewhat more mundane factoids of science, they come blazing back with remarkable gusto. today's class was on centripetal force, that fantastic force that keeps objects moving in a circle although they'd rather be moving in a straight line, that keeps sweet earth orbiting the sun, the moon the earth, and allows me to do wacky demonstrations in class. the first thing i did was tie a roll of tape to a string and swing it around in a circle in the front of the class, ala lifeguard twirling a whistle. i asked what would happen if the force, or string, all of a sudden was gone and the tape could move as it wanted, i.e. in a straight line? as the students were about to answer, i would let go of the tape and it would go flying into the ceiling, into equipment at the side of the blackboard, into the cabinets, wherever. i knew i was doing my job when the kids all flinched as i made a move to pick up another object. that flinch = they're assuming i'm about to throw something or squirt them in the face. awesome.
the other demonstration i did involved filling a bucket with water and then swinging it around in a circle. amazingly, the water does not fall out of the bucket and instead stays trapped inside... and who knew that this little demonstration was going to blow the roof off the building. i start swinging the bucket and the kids are on the desks, losing their minds, screaming "don't do it!", and then boom... i do it and the room erupts. kids are shaking their heads exclaiming "lord have mercy," others are pumping their fists into the air, others are slack jawed and just staring into space.
water in a bucket.
4 comments:
To paraphrase XKCD: "Science, it works bitches"
You're calling it "centripetal" force, while others call it "centrifugal", and the fact of the matter is that there is no such force whatsoever. It is simply an example of a body in motion tending to stay in motion unless acted on by some outside force or object, in this case the object being the bucket which the water cannot pass through.
I'm homeschooling my kids,
whatevah, Zachary. I'm homeschooling my kids too and they'll grow up to know that circles, like all shapes, have their own forces just like OPD says; like the awesome cubical force, which forces all things in cubes to become cube shaped. also, sphenoids with a force that can only be described as magical.
actually, zachary, centrifugal force is the force that supposedly opposes the centripetal force of any object moving in a circle. but since the existence of both of them is debatable, we'll attribute that center-seeking force to the center-seeking zombie fairies.
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