Ocanos de agua y aire: manual del usuario

Orlando Guzmn rea de fsica de lquidos

UAM-Iztapalapa

1: Hidrosttica Material:

Regla de 30 cm

Hoja de papel

Por qu es diferente el resultado:

con o sin la hoja de papel?

con la hoja plana o arrugada?

Presin atmosfrica

Presin atmosfrica a nivel del mar (media de 15 aos) para junio, julio, y agosto (arriba) y

diciembre, enero, y febrero (abajo).

4,300 m 2,700 m 300 m

Altura Latitud

Mundos con ocanos?

Mundos con ocanos?

Enceladus

Europa

2: Hidrodinmica

Published by the MUSE group (More Understanding with Simple Experiments) February 2011 in the Physics Education Division (PED) of the European Physical Society (EPS) http://education.epsdivisions.org/muse/

2

Two figures from Atkins paper (1988)

As shown by Slisko (GIREP-EPEC 2009, see also Slisko & Corona Cruz 1997), a similar misleading drawing was included by Leonardo da Vinci in his book Del moto e misura dell' acqua.

Figure 3: A similarly misleading drawing from Del moto e misura dell' acqua by Leonardo da Vinci, digitised copy from Harvard College Library, Google books. Slisko (1997, 2009) has also demonstrated that, a century after Leonardo da Vincis drawing, the issue was correctly resolved by Torricelli around 1640 and was correctly dealt with by most textbook authors during the 19th century. However, the erroneous prediction and the misguided association of this measurement with hydrostatic pressure resurfaced again in textbooks of the 19th century and have remained with us since then (see for instance Santamaria 2007).

Cmo se veran los chorros si hacemos el experimento? Haz tu dibujo

2: HidrodinmicaPublished by the MUSE group (More Understanding with Simple Experiments) February 2011 in the Physics Education Division (PED) of the European Physical Society (EPS) http://education.epsdivisions.org/muse/

2

Two figures from Atkins paper (1988)

As shown by Slisko (GIREP-EPEC 2009, see also Slisko & Corona Cruz 1997), a similar misleading drawing was included by Leonardo da Vinci in his book Del moto e misura dell' acqua.

Figure 3: A similarly misleading drawing from Del moto e misura dell' acqua by Leonardo da Vinci, digitised copy from Harvard College Library, Google books. Slisko (1997, 2009) has also demonstrated that, a century after Leonardo da Vincis drawing, the issue was correctly resolved by Torricelli around 1640 and was correctly dealt with by most textbook authors during the 19th century. However, the erroneous prediction and the misguided association of this measurement with hydrostatic pressure resurfaced again in textbooks of the 19th century and have remained with us since then (see for instance Santamaria 2007).

Anlisis Velocidad de salida:

Principio de Bernoulli

Tiempo de cada:

Distancia recorrida: x = v1t

Published by the MUSE group (More Understanding with Simple Experiments) February 2011 in the Physics Education Division (PED) of the European Physical Society (EPS) http://education.epsdivisions.org/muse/

5

tff = [2 (h+a)/g]1/2

d= vh tff = 2 [(H-h)(h+a)]1/2

Figure 4 illustrates two cases: The standard picture and the more generalized case, where the standard jets may change the ranking of the ranges with respect to the red line.

Figure 4. The generalized solution to the water jets problem. Two situations can be observed: (a) the standard picture, where the three jets impact the horizontal surface shown in black, and (b) the more generalized case, where the water jets may change the ranking of their ranges (eg with respect to the horizontal surface shown in red).

In the case represented in Figure 4, when the ranges increase with the distance from the hole to the free surface, there is a risk of misunderstanding. The outcome of the experiment may reinforce two misleading intuitions. One is that the pressure at the exit hole increases with this distance, as in a static case, whereas the Bernoulli theorem has been used considering that this pressure was the atmospheric pressure. The other possible wrong idea is that the range of the jets only depends on the exit velocity, whereas it still also depends on the time of free fall.

An effort to compare detailed observations with numerical modeling of this effect reveals additional complexities with respect to the viscosity of the liquid and the size and shape of the fluid jet hole. Figure 5 presents theoretical predictions (red curves) superimposed on a photograph of the jet streams. Likewise, hot and cold water behave differently due to the corresponding change in viscosity. A detailed analysis of these complexities will follow in a separate paper in the future.

const. =v212

+ gh+p1

=v222

+ gH +p2

v1 =p2g(H h)

h =1

2gt2

t =

s2h

g

x = 2ph(H h)

RevisinPublished by the MUSE group (More Understanding with Simple Experiments) February 2011 in the Physics Education Division (PED) of the European Physical Society (EPS) http://education.epsdivisions.org/muse/

2

Two figures from Atkins paper (1988)

As shown by Slisko (GIREP-EPEC 2009, see also Slisko & Corona Cruz 1997), a similar misleading drawing was included by Leonardo da Vinci in his book Del moto e misura dell' acqua.

Figure 3: A similarly misleading drawing from Del moto e misura dell' acqua by Leonardo da Vinci, digitised copy from Harvard College Library, Google books. Slisko (1997, 2009) has also demonstrated that, a century after Leonardo da Vincis drawing, the issue was correctly resolved by Torricelli around 1640 and was correctly dealt with by most textbook authors during the 19th century. However, the erroneous prediction and the misguided association of this measurement with hydrostatic pressure resurfaced again in textbooks of the 19th century and have remained with us since then (see for instance Santamaria 2007).

Lagos y ros de hidrocarburos en Titn

3: Efecto Coriolis Material:

1 hoja de papel

Lpiz

Dibuja un crculo en el centro de la hoja

Lentamente, traza una lnea del centro al exterior, mientras giras la hoja en sentido contrario a las manecillas del reloj:

haca adonde se desva la lnea?

hacia dnde se desva si trazas la linea del exterior al centro?

Ciclones

El centro del cicln tiene baja presin. El aire tiende a fluir hacia el centro (azul), pero el efecto Coriolis lo desva perpendicularmente a su velocidad (rojo). El equilibrio se alcanza con un movimiento circular, perpendicular al gradiente de presin (flujo geostrfico).

4: Ondas y termodinmica

El aire se mueve en 3D. Al subir, se expande y se enfra, y el vapor de agua se condensa en nubes. Al bajar, el aire se comprime y se calienta, el agua se evapora y las nubes se disipan. Este ciclo se repite muchas veces, a lo largo de cientos de kilmetros.

4: Ondas y termodinmica

El aire se mueve en 3D. Al subir, se expande y se enfra, y el vapor de agua se condensa en nubes. Al bajar, el aire se comprime y se calienta, el agua se evapora y las nubes se disipan. Este ciclo se repite muchas veces, a lo largo de cientos de kilmetros.

Para concluir

Para estudiar el clima de la Tierra, bastar con estudiar un slo ejemplo de ocano y atmsfera?

Para estudiar los ocenos y atmsferas del sistema solar, qu ramas de la ciencia se necesitarn?