# Does it affect the hemisphere actually sense that the water tour?

We show what the Coriolis effect, which explains the direction of rotation of water in each hemisphere of the planet Earth.

One of the great myths traveler says the sense in which water from a bathtub tour (or any element with a drain) changes depending on the hemisphere in which we find ourselves. In fact, The Simpsons devoted to an episode of to this myth.

But is this really true? Does it affect the hemisphere the direction of rotation of the water? The reality is that, like many myths, has a real part and a false part.

## Understanding the Coriolis

The primary responsibility for this alleged event is the Coriolis effect. This effect, caused by earth movements performed constantly (translation and rotation), alters the trajectories of any mass to rotate about the same point . This can be both water compared to a drain as the clouds relative to the eye of a hurricane.

But to understand this effect, we must first know the differences between the angular and linear velocities an element moving experience

The angular velocity is a magnitude with which the rotational speed about a point is measured. This does not depend on the radius of curvature but the angle rotated in a given unit of time. However, the linear speed does vary depending on the radio path. In fact, the linear velocity is known as v = ω xr , where “v” is the linear velocity “ω” the angular velocity and “r” the radius of gyration.

To better understand this concept, think of a parabolic curve of 180 degrees in which two cars come simultaneously and in parallel. If both cars run through at 50km / h, the car is closer to the inside of the curve (smaller radius of curvature) come to an end before that you take it on the outside (larger radius curvature), because the path ahead is less.

The greater the radius of curvature, the smaller the angular velocity For both cars complete the curve the same time, you need the car “and” travel the curve on the outside increase your speed (linear) and managing to stay parallel to the drive “x” (which is at 50km / h ). In that case, both cars have different linear velocities, but maintain the same angular velocity, then “walking” the same 180 degrees in the same unit of time.

Something similar happens on Earth. An element located on the north or south pole take 24 hours to return to the same point. In the same way that an element found in Ecuador. Both therefore maintain the same angular velocity (walking in 24 hours 360).

Instead, the element at the north or south of the Earth poles has a lower linear velocity . that which is in the Ecuador , because the distance (in meters) to cover is considerably less

Knowing this, understanding the Coriolis effect is as simple as seeing the following GIF:

In it we see how the linear velocity of an element” a “located more next to Ecuador is greater (“long” vector), while the linear velocity of a “b” element located closer to the pole is smaller (the magnitude of the speed vector is low). For its part, the speed of the intermediate point “c” takes an average value for the points “a” and “b”. These speeds act in an interval (x, x) , that is, from left to right.

Depending on the hemisphere, the particles more time linear zone will be higher or lower When the elements are approaching the common point called “c” (begin to share the same path), the item “a” (more linear velocity) will come on and the Item “b” (less linear speed) will be delayed. This is because linear velocity of the element “a” is greater than the characteristic of the element “c” , ahead of this; while the item “b” is less than that of element “c”, lagging about this.

To understand this, we will do with the car analogy. If the car “x” that circulates inside of the curve shifts to the outside of the curve (while maintaining its speed 50km / h), it will start to travel the same path as the car “and”. But considering that the linear velocity is less than “and” will stand behind this and end the curve later.

When water particles undergo several action of those forces, begin to generate a turn clockwise or counterclockwise. This depends on the hemisphere in which we find ourselves. If we are in the northern hemisphere, the particles of the upper half will have less line speed, so be delayed and will generate a turn counterclockwise. But if we are in the southern hemisphere, the particles of the upper half will have greater linear speed, so they will advance and generate a turn clockwise.

Then What is false in this belief?

As we have seen, the Coriolis effect does affect the direction of rotation of various elements on the Earth’s surface such as hurricanes or water. The “but” is not taken into consideration is that the strength of the Coriolis effect is very low, so often not unduly affecting small mass . Thus, the direction of rotation of a drain water is more influenced by other factors such as the origin of the jet or the shape of the sink itself.

Hypertext

Does it affect the hemisphere actually sense that the water tour?
Source: english
September 6, 2015