why does the rotation of any object goes counter-clock wise?

Question

all 90,180,270, and 360 degree rotations go counter clockwise...why?

Answer 1

We simply have a CONVENTION, which was agreed to long ago and maintained ever since :

We measure rotation in the plane as POSITIVE when the polar coordinate angle increases from 0 though 90,180,270, and 360 degrees. One in the OPPOSITE (clockwise) direction is given a NEGATIVE sign.

This is also consistent with what is called a "right-hand screw sense of rotation" about a z-axis that points UPWARD, perpendicularly out of the paper on which a conventional pair of x- and y-axes are drawn. (On the paper, looked at the usual "right way up," the x-axis goes to the right, and the y-axis is perpendicular to that and goes towards the "top edge" of the paper.)

If you look ALONG the z-axis, FROM the origin of co-ordinates, a POSITIVE rotation (as already described) involves a CLOCKWISE rotation. That's the explanation for conventionally calling it the so-called "right-hand screw sense of rotation." This looks opposite from what you see when you LOOK DOWN on the paper, because you are now looking along an OPPOSITELY-DIRECTED AXIS, namely in the NEGATIVE z-direction, instead of in the POSITIVE z-direction. [ ### : See LATER FOOTNOTE, below. ]

If this still puzzles you, get hold of a bicycle wheel and a cooperative friend. Hold the wheel out in front of you and spin it slowly in the "right-hand sense," that is CLOCKWISE from your point of view. Now ask your friend what he or she sees. (They should answer "It's rotating ANTI-CLOCKWISE!")

It's because of this possible confusion about what one means by a "positive rotation," that it is necessary to have some standard convention about how to draw axes and how to measure rotation or its associated consequences like "spin rate" or "angular momentum," etc. For that, there are only two fully consistent choices: the right-hand screw sense for everything, or the left-hand screw sense for everything. Science opted for the right-hand screw sense at least a century or more ago, so that's what we all use.

Once you've conquered and understand this idea, look in the mirror. In IT, the POSITIVE axis coming out of the mirror is REVERSED in the reflections that you see, in a sense in "the world behind the mirror." Now rotate something out in the real world, in the clockwise or right-hand sense. It simply doesn't matter what axis it's around, you'll find it's rotating in a left-hand screw sense in "mirror world."

If you have a friend studying physics who is used to remembering or illustrating a right-hand rotation with his or her thumb and two fingers of the right-hand (their ****** head, crossed eyes and twisted look on the face are all just added attractions!) , get them to stand in front of the mirror and do just that again. You'll both notice that the counterpart in mirror world is perversely using his or her LEFT-HAND to illustrate the LEFT-HAND screw sense of rotation!

All of these bizarre effects occur because of one single thing --- the REVERSAL of just one coordinate axis from pointing OUT of the mirror's surface to pointing INTO it. That alone changes our world's right-hand screw sense for everything into a left-hand screw sense in mirror world.

Mind-blowing!

Live long and prosper.

### LATER FOOTNOTE: This explains the point that puzzled 'Mc Duff,' three responses later, below.

Answer 2

I know what your saying, check this out; flush your toilet; if your in North America it goes clockwise and in Australia it goes counter clockwise; it has to do with the Earths rotation and torque; you can flush without using the toilet as it makes for a better visual effect. :)

Answer 3

It's just an arbitrary direction that was agreed upon a long time ago to be a standard for mathematical purposes of giving a meaning to the sign of an angle........

Answer 4

I always thought the standard (to avoid confusion) was
clockwise NOW i'm confused

Answer 5

Not if you look from underneath.