Triple Twirl

By -
Select an object having approximately uniform density throughout and in the shape of a rectangular solid with no two sides equal. Almost any hardcover book will do nicely.

Let the three axes between the centers of opposite pairs of faces be labeled X, Y, Z: the X-axis is the longest, the Z-axis is the shortest, and the Y-axis is intermediate.

Pick up the object in both hands along one of the axes and toss it gently into the air, twirling it about the axis. About the X-axis it will rise, fall, and twirl stably, and about the Z-axis likewise. About the Y-axis it never will, no matter how carefully you toss it. Try it if you don’t believe me. It’s quite mind-boggling to experience.

Now, come back here and explain, please.

Comments

  1. John Goes7:13 PM

    I did it easily, so I'm guessing I cheated in some way. About the x axis it flipped the book top over bottom, about the y it flipped side over side, about the z it twirled around 360 degrees. Did I apply illegal vector forces?

    ReplyDelete
  2. Anonymous11:38 AM

    They should all be 360 rotations!

    ReplyDelete
  3. John Goes12:41 PM

    twirled in a circle along the xy axis, i mean, like when you twirl pizza dough.

    ReplyDelete
  4. John Goes1:38 PM

    This comment has been removed by the author.

    ReplyDelete
  5. John Goes1:39 PM

    err..not on the xy axis, but twirling ON the xy PLANE, about the z axis.

    ReplyDelete
  6. Wabulon5:31 PM

    I meant it in the way john described it in his just previous comment. I didn't understand what anonymous was getting at.

    ReplyDelete
  7. John Goes1:50 AM

    Wabulon, I didn't get it, though. I was able to twirl the book around all axes. Did I apply illegal vector forces? Can you be more specific how I may throw the book?

    ReplyDelete
  8. Wabulon6:26 PM

    Say we're going to use the X-axis. Lay the book on the table with the X-axis parallel to the edge of the table nearest you. Lay your hands upon the book at either end. Slip your second or third fingers under the book. Lift, holding the book between your first few fingers and thumb. Toss, lifting your fingers and depressing your thumbs as you do so, giving the book a spin.

    ReplyDelete
  9. Anonymous8:54 AM

    What I find is that it wobbles in the Y axis but flips smoothly in the X and Z axes.

    ReplyDelete
  10. Wabulon5:33 PM

    Thank you, susan--at least one person agrees with God and me.

    ReplyDelete

Post a Comment

Popular posts from this blog

Libertarians, My Libertarians!

By -
Cruel to be kind means that I love you . Because, while I think you are mistaken, your hearts are in the right place -- yes, even you, Silas --  unlike some people . This Breitbart fellow (discussed in the link above), by all appearances, deliberately doctored a video of Shirley Sherrod to make her remarks appear virulently racist, when they had, in fact, the opposite import. I heard that at a recent Austrian conference, some folks were talking about "Callahan's conservative turn." While that description is not entirely inaccurate, I must say that a lot of these people who today call themselves conservative give me the heebie-jeebies.
Read more

"Pre-Galilean" Foolishness

By -
 I am currently reading The Master and His Emissary , which appears to be an excellent book. ("Appears" because I don't know the neuroscience literature well enough to say for sure, yet.) But then on page 186 I find: "Asking cognition, however, to give a perspective on the relationship between cognition and affect is like asking astronomer in the pre-Galilean geocentric world, whether, in his opinion, the sun moves round the earth of the earth around the sun. To ask a question alone would be enough to label one as mad." OK, this is garbage. First of all, it should be pre-Copernican, not pre-Galilean. But much worse is that people have seriously been considering heliocentrism for many centuries before Copernicus. Aristarchus had proposed a heliocentric model in the 4th-century BC. It had generally been considered wrong, but not "mad." (And wrong for scientific reasons: Why, for instance, did we not observe stellar parallax?) And when Copernicus propose...
Read more