Why are races always run in a counterclockwise direction?

[Irishman]

@TriPolar

On a side note from the which-wise discussion, the description of the Moon’s path orbiting the Earth is confusing at a minimum. The Moon and the Earth co-orbit the Sun together. Decriptions of relative movement can be ambiguous not only in terms of the direction, but the type of motion as well.

I wouldn’t refer to that site. It is full of antiscientific hooey, like the Expanding Earth and disbelief in Plate Technonics.

If you wish to point out the peculiarity of the Moon’s orbit, just point at wikipedia.

In representations of the Solar System, it is common to draw the trajectory of the Earth from the point of view of the Sun, and the trajectory of the Moon from the point of view of the Earth. This could give the impression that the Moon circles around the Earth in such a way that sometimes it goes backwards when viewed from the Sun’s perspective. Since the orbital velocity of the Moon about the Earth (1 km/s) is small compared to the orbital velocity of the Earth about the Sun (30 km/s), this never occurs. There are no rearward loops in the Moon’s solar orbit.

[snip]

Unlike most moons in the Solar System, the trajectory of the Moon around the Sun is very similar to that of Earth. The Sun’s gravitational effect on the Moon is over twice as great as the Earth’s on the Moon; consequently, the Moon’s trajectory is always convex[13][14] (as seen when looking Sunward at the entire Moon/Earth/Sun system from a great distance outside the Earth/Moon solar orbit), and is nowhere concave (from the same perspective) or looped.[12][13][15]

As wikipedia explains, there is nothing inaccurate with saying the Moon orbits Earth. The Moon has points in it’s orbit where it is sequentially ahead of Earth, between Earth and the Sun, behind Earth, and on the far side of Earth from the Sun. The shape of the path of the Moon with respect to the Sun is by virtue of the solar orbital velocity versus the orbital velocity around Earth. It is perhaps not easily realized, but it is inherent in the vector mathematical relationships.

[TriPolar]

@Irishman

I wouldn’t refer to that site. It is full of antiscientific hooey, like the Expanding Earth and disbelief in Plate Technonics.

Good point about that. I was looking for something with a diagram, should have stuck to the wordy but more accurate description.

[Learjeff]

@Irishman

Take that up with the people who invented the unit circle.

I believe we can blame the direction of the unit circle on Descarte, who made the X axis increase going from left to right (assuming Y axis increase from bottom to top is less arbitrary … sorta). Given the direction of the axes, there’s only one direction the unit circle can go around.

At least, not without changing the definitions for sine and cosine.

[Learjeff]

@TriPolar

On a side note from the which-wise discussion, the description of the Moon’s path orbiting the Earth is confusing at a minimum. The Moon and the Earth co-orbit the Sun together. Decriptions of relative movement can be ambiguous not only in terms of the direction, but the type of motion as well.

If you say the moon doesn’t orbit around the Earth, then you also have to say that the Earth doesn’t orbit around the Sun.

The Moon and Earth orbit around their collective center of gravity, just as they both orbit as a system around their collective center of gravity with the Sun.

And of course, that’s just an approximation, too, because they all orbit around the Milky Way, and all orbits are affect by all other planets, and every damn bit of dust in the universe.

As approximations and for illustrative purposes, it does make sense to say that the Moon orbits around the Earth. However, if you’re plotting the orbits, you don’t calculate it that way.

[agnesnitt]

Most (but not all) ice rinks will ‘turn the ice’ midway through a public skating session so that the beginning of the session starts counter-clockwise then at half time there’s a horn or an announcement and the people skate clockwise. At rinks that do this, the counter-clockwise session is first.
I noticed that this phenomenon occurs mostly at rinks above the Mason-Dixon line.

[Powers]

@agnesnitt

Most (but not all) ice rinks will ‘turn the ice’ midway through a public skating session so that the beginning of the session starts counter-clockwise then at half time there’s a horn or an announcement and the people skate clockwise. At rinks that do this, the counter-clockwise session is first.
I noticed that this phenomenon occurs mostly at rinks above the Mason-Dixon line.

There are rinks south of the Mason-Dixon line?
Powers &8^]

[Irishman]

Sure - artificial, but rinks nonetheless. Houston had one set up on Discovery Green downtown.

[agnesnitt]

@Powers

There are rinks south of the Mason-Dixon line?
Powers &8^]

There are many, many rinks south of the Mason-Dixon line, and they’re real ice too, not artificial. However, mostly in larger cities. Though there is a large training rink in Frisco, Texas which makes my jaw drop. I remember when Frisco was fields, a city hall , and 3 schools.

[Kenm]

The term “artificial ice” is something of a misnomer. It is basically frozen water just like any other. The difference is, it is not frozen by natural cold outdoors such as on a frozen pond or lake. It is frozen indoors by the installed refrigeration system.

…

[agnesnitt]

Kenm thank you for the clarification.
It shows an interesting geographical divide. Since I live where there’s nothing but man-made ice, we don’t think of it as artificial. We think of synthetic ice as being artificial ice. Naturally frozen ice is called ‘pond ice’. I suspect if I lived in Canada, the distinctions you identified would be used.

[Irishman]

I did not say “artificial ice”. I said “artificial” but meant the rinks were artificial, i.e. not naturally frozen ponds and lakes, but floors covered by frozen water. Like indoor hockey rinks. You know, with a Zamboni.

But there is a kind of synthetic ice - one of the groups on America’s Got Talent this year was an ice show/aerial act. They used some sheets of some type of plastic to allow them to set up their ice skating rink anywhere, such as the stage at Radio City Music Hall. They used regular ice skates. But that’s a totally different and new thing, as opposed to manmade ice rinks.

[Powers]

I was being facetious. Sorry for not including a smiley. =)
Powers &8^]

[Mustydope]

I’d like to offer an alternative explanation. As we all know most of the people including athletes are right handed and their right legs are usually more powerful. If you try to walk or run for a long time without any guiding lines to show your exact direction or location you’ll inevitably run in a circle. And because of the more powerful right food has a bigger step and a more powerful push you’ll run in a counterclockwise direction. I believe this may be the reason for that tradition of the races.

[Senegoid]

Be it noted that we Merkins take perverted pleasure in doing all kinds of things bass-ackwards from the way the rest of the world works. Carousels likewise run clockwise (seen from above) everywhere else that I know of, but counter-clockwise in America. I assume this must be patterned after real-life horse racing and horse showing.

When those elaborately carved and painted carousel horses get moved across the Pond from one carousel to another, they have to get repainted and redecorated to swap their show sides from their off sides. Take a closer look some time. Yes, even carousel horses have an elaborately decorated show side and a somewhat plainer off side.

[watchwolf49]

Counter-clockwise motion in the northern hemisphere takes advantage of the Coriolis Effect, it actually takes less energy input because we’d get a boost from gravitation.

[John_W.Kennedy]

A) The Coriolis Effect is negligible on that scale.

B) “Gravitation”? What “gravitation”?

[watchwolf49]

A) Negligible compared to what? If there are no other torques being applied, then the Coriolis Effect dominates. For a typical two hour race, it’s about a 1/12th lap advantage (2hr:24hr::30º:360º). Remember, the grandstands are a non-Newtonian frame of reference.

B) Gravitation is the force vector perpendicular to the rotation of axis, as opposed to gravity which is normal to the surface. My chair here in Monaco doesn’t orbit the earth, it’s fixed to the surface with a motion distinctly non-Keplerian.

[ZenBeam]

@watchwolf49

A) Negligible compared to what? If there are no other torques being applied, then the Coriolis Effect dominates. For a typical two hour race, it’s about a 1/12th lap advantage (2hr:24hr::30º:360º). Remember, the grandstands are a non-Newtonian frame of reference.

Can you show your work here? Some equations so we can understand what you’re trying to say.

B) Gravitation is the force vector perpendicular to the rotation of axis, […]

What do you mean by “rotation of axis”? Do you mean “axis of rotation”? If so, do you mean the axis of the Earth’s rotation, or some other axis of rotation? If you mean “axis of the Earth’s rotation”, where did you get that definition from? Never heard of it, and I don’t see where it would be at all useful.

[Floater]

@watchwolf49

Counter-clockwise motion in the northern hemisphere takes advantage of the Coriolis Effect, it actually takes less energy input because we’d get a boost from gravitation.

When talking about the Coriolis effect it should be noted that the terms clockwise and counter-clockwise motion is limited to the Northern hemisphere, so a better terminology is sunwise and counter-sunwise, which covers both halves of the World. That said: the Coriolis effect causes winds to move sunwise, i.e. to the right on the Northern hemisphere and to the left in the antipodes. But then again, cyclones rotate counter-sunwise, in the opposite direction as caused by the Coriolis effect, which is clearly seen in this photo. I find it strange that nobody has pointed this out earlier.

Let me add a question of mine own: How do much smaller weather systems like tornadoes rotate, counter-sunwise like cyclones or any direction?

[Irishman]

[QUOTE=Mustydope]
I’d like to offer an alternative explanation. As we all know most of the people including athletes are right handed and their right legs are usually more powerful. If you try to walk or run for a long time without any guiding lines to show your exact direction or location you’ll inevitably run in a circle. And because of the more powerful right food has a bigger step and a more powerful push you’ll run in a counterclockwise direction. I believe this may be the reason for that tradition of the races.
[/QUOTE]

While in theory this argument makes sense, in practice it is hogwash. The Mythbusters demonstrated conclusively that your sense of balance and coordination are such that the path you walk can vary essentially randomly. Now, maybe on a perfectly flat surface with no obstacles you would tend to dominate your strong side, but in any real conditions this just isn’t so.

[QUOTE=watchwolf49]
A) Negligible compared to what? If there are no other torques being applied, then the Coriolis Effect dominates.
[/quote]

A typical race includes far greater forces than coriolis. Other torques include the friction with the ground applied to create a turn.

For a typical two hour race, it’s about a 1/12th lap advantage (2hr:24hr::30º:360º). Remember, the grandstands are a non-Newtonian frame of reference.

If I parse your statement correctly, you’re making the relation

2hr/24hr = 30º/360º

i.e. 2hr = 1/12 of a day, 1 day = 1 full rotation = 360º, 1/12 x 360º = 30º

You’re apparently then trying to say that 30º rotation means that the car gets a 30º boost. I don’t think it works that way.

[QUOTE=ZenBeam]
What do you mean by “rotation of axis”? Do you mean “axis of rotation”? If so, do you mean the axis of the Earth’s rotation, or some other axis of rotation? If you mean “axis of the Earth’s rotation”, where did you get that definition from? Never heard of it, and I don’t see where it would be at all useful.
[/QUOTE]

Looking at wikipedia:

Newton’s laws of motion describe the motion of an object in a (non-accelerating) inertial frame of reference. When Newton’s laws are transformed to a uniformly rotating frame of reference, the Coriolis and centrifugal forces appear. Both forces are proportional to the mass of the object. The Coriolis force is proportional to the rotation rate and the centrifugal force is proportional to its square. The Coriolis force acts in a direction perpendicular to the rotation axis and to the velocity of the body in the rotating frame and is proportional to the object’s speed in the rotating frame. The centrifugal force acts outwards in the radial direction and is proportional to the distance of the body from the axis of the rotating frame. These additional forces are termed inertial forces, fictitious forces or pseudo forces. They allow the application of Newton’s laws to a rotating system. They are correction factors that do not exist in a non-accelerating or inertial reference frame.

I think he just typoed phrasing. As far as “gravitation”, he’s apparently trying to take the combined centripetal force effect of the Earth’s rotation into effect, to differentiate the perceived weight versus the pure effect of attraction of mass (i.e. “gravity”). In other words, you weigh slightly less at the equator than the poles because of the rotation of Earth at the equators, neglecting altitude effects.

[QUOTE=Floater]
When talking about the Coriolis effect it should be noted that the terms clockwise and counter-clockwise motion is limited to the Northern hemisphere, so a better terminology is sunwise and counter-sunwise, which covers both halves of the World.
[/quote]

I don’t understand how “sunwise” makes any sense. Is that meant to imply the direction shadows track or something? I don’t see how that is easily understood.

That said: the Coriolis effect causes winds to move sunwise, i.e. to the right on the Northern hemisphere and to the left in the antipodes. But then again, cyclones rotate counter-sunwise, in the opposite direction as caused by the Coriolis effect, which is clearly seen in this photo. I find it strange that nobody has pointed this out earlier.

That is a curious feature. It is actually discussed under the Meteorology section of the wikipedia page. The key factor is the behavior of high and low pressure systems.

High pressure systems rotate in a direction such that the Coriolis force will be directed radially inwards, and nearly balanced by the outwardly radial pressure gradient. This direction is clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere. Low pressure systems rotate in the opposite direction, so that the Coriolis force is directed radially outward and nearly balances an inwardly radial pressure gradient. In each case a slight imbalance between the Coriolis force and the pressure gradient accounts for the radially inward acceleration of the system’s circular motion.

Cyclones are low pressure air systems, so the rotation is controlled by air moving inward. If you look at the diagram under the “Flow around low pressure area” header, you see how the rotation of the air mass is affected by coriolis trying to deflect air right (clockwise), as air moves inward from all directions (pressure gradient). This creates a vortex rotating counterclockwise.

Let me add a question of mine own: How do much smaller weather systems like tornadoes rotate, counter-sunwise like cyclones or any direction?

A significant non-dimensional factor for assessing the effect of coriolis on a rotating system is the Rossby number.

A small Rossby number signifies a system which is strongly affected by Coriolis forces, and a large Rossby number signifies a system in which inertial and centrifugal forces dominate. For example, in tornadoes, the Rossby number is large (≈ 103), in low-pressure systems it is low (≈ 0.1 – 1) and in oceanic systems it is of the order of unity, but depending on the phenomena can range over several orders of magnitude (≈ 10−2 – 102). As a result, in tornadoes the Coriolis force is negligible, and balance is between pressure and centrifugal forces (called cyclostrophic balance).

With regards to car races:

When the Rossby number is large (either because f is small, such as in the tropics and at lower latitudes; or because L is small, that is, for small-scale motions such as flow in a bathtub; or for large speeds), the effects of planetary rotation are unimportant and can be neglected.