Earth – a somewhat bigger laboratory for school Physics
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Transcript of Earth – a somewhat bigger laboratory for school Physics
Earth – a somewhat bigger laboratory for school Physics
Grzegorz Karwasz
Andrzej Karbowski
Krzysztof Służewski
http://dydaktyka.fizyka.umk.pl
Zakład Dydaktyki Fizyki, Uniwersytet Mikołaja Kopernika w Toruniu
XIV: Structure and evolution of Earth
• Litosphere
• Hydroshere
• Atmosphere
• (Crysphere)
• Biosphere
XV: Structure and evolution of Solar System
Didactical/ heurestic goal
• Bring together Physics & Geography• Illustrate, possibly experimentally, phenomena• Choose the minimum knowledge requirements• Make the whole package attractive
Didactical theory context: -neo-realism (show as much as you can,
and even more), -hyper- constructivism (make student construct his/ her knowledge from apparently nothing, i.e. pre-existing knowledge in his/her mind)
G. Karwasz, Problemy Wczesnego Nauczania, 2013G. Karwasz, GIREP Conference 2012
Case examples:
- radioactivity → the age of Earth
- two-body mechanics → Earth and Moon
- gravity and rotation → shape of Earth
- convection and radioactivity → shield tectonics
- electromagnetic induction → magnetic field
- Coriolis force → general dynamics of atmosphere
- Coriolis force → dynamics of oceanic currents
- latent heat & convection → tropical storms
Three heurestic functions of an interactive/multimedia object
- Child: that’s so funny!
- Pupil: that’s so easy!
- Scientist: that’s so complex!
G. Karwasz, J. Kruk, Idee i realizacje dydaktyki interaktywnej, Wyd. Nauk. UMK, 2012
Radioactive series
rad - 1600 lat, gaz radon - 3,8 dnia, polon - 3 minuty, ołów - 27 minut (ten rozpada się przez proces β); bizmut - 20 minut; w kolejnym rozpadzie β powstaje ponownie polon, ale inny izotop, żyjący zaledwie 0,16 milisekundy, itd.
In other words:- a starting point 238U- some „bottle necks”- an ending point 206Pb
What is the age of Earth?
Science 321, 1828 (2008); Jonathan O'Neil, et al. Neodymium-142 Evidence for Hadean Mafic CrustScience 309, 576 (2005); M. Boyet, et al. Silicate Earth 142Nd Evidence for Early (>4.53 Ga) Global Differentiation of the Silicate Earth
Moon – a companion from (almost) ever
http://en.wikipedia.org/wiki/Lunar_eclipse
4.567 bln yrs + ~100 mln yrs ago
„Satelite” = body guard
G. Karwasz, M. Więcek, Toruński po-ręcznik. Fizyka współczesna, ZDF UMK 2012
„Satelite” = orbit stabilizer
→ destabilisation of Earth’s axis in 100 mln yrs
Physics and Toys
„Jakiego kształtu jest kula ziemska?”What is the shape of Earth’s ball?Answer: „Geoide” = Earth-like shape
= tautologyFoto: ESA
https://directory.eoportal.org/web/eoportal/satellite-missions/content/-/article/goce
Copernicus: Why water does not flow down from Earth’s ball?
remained: „what is the shape of Earth?”
Newton: Because of gravity
Także i wody morskie układają się do postaci kulistej [...]
jako ląd i woda wspierają się na jednym środku ciężkości Ziemi, który jest zarazem środkiem jej objętości.
Newton: Elipsoid
because of the centrifugal force
Springs in mountains flow perpendicularly to iso-height lines
In physics we call these lines - equi-potential lines:the gravity force is perpendicular to potential lines
Ellipsoid vs. geoid
i.e. geometry vs. physics
Geoid – constant (gravitational + centrifugal) potential surface
GOCE: equipotential lines
https://directory.eoportal.org/web/eoportal/satellite-missions/content/-/article/goce
Earth’s shape: equipotential surface
± 100 mhttps://directory.eoportal.org/web/eoportal/satellite-missions/content/-/article/goce
Earth’s shape: equipotential surface
Geoid is lower than elipsoid in the Himalaya mountains!
Potential formula: V=GM/r2
Lower mass → lower r
Himalaya are ligth (calcite) rocks
What is the shape of Earth?
The one, shown by the lever (libella)
and this is perpendicular to the verticalPoziomica, pion
Earth’s shape: horizontal water
because water level is always horizontal, like Copernicus said
What is the Earth’s internal structure?
S-wave in iron: 3,24 km/s
P-wave in iron: 5,95 km/s
Sprężyny, stukot
What is the Earth’s structure?
G. Karwasz, J. Chojnacka, Geografia w Szkole, 2012
crust ↔ litospheremantello ↔ astenosphere
How old is Europe?
M. Grad, T. Tirra, and ESC Working Group, The Moho depth map of the European Plate, Geophys. J. Int. 176 (2009), str. 279.
Why this vertical movement?
Physics World, March 2013
Heat flux:
- 238U: 8 TW (1015 W)- 232Th: 8 TW- 40K: 4 TW- cooling: 20 TW
- (electricity production: 10 TW)
Geo-fizyka dla nie-fizyków
Justyna ChojnackaZakład Dydaktyki Fizyki
Wydział Fizyki, Astronomii i Informatyki Stosowanej
300 mln yrs ago
„Pangea”
Colliding continents (I)
John Nábelek, et al. Science 325, 1371 (2009); Foto: J. Karwowski, M. Karwasz, M. Visintainer
Colliding continents (III)Subduction of oceanic plates
Ryc. K. Konieczna
Physics World, no 3. (2012)
Auto-generated electric super-currents →auto-generated magnetic fields
389371aa.eps.2.gifIllustration of the dynamo mechanism that creates the Earth's magnetic field
Atmosphere: Tropics and trade winds
Why Tropics are high pressure regions?
It is dry (descending) air!
subtropical and polar jet streams
Atmosphere: Columbus plan
Seasonal changes in Earth’s axis anglebetween September and March (1492/3)
http://earthguide.ucsd.edu/virtualmuseum/images/ColumbusRoute.html
http://wps.prenhall.com/wps/media/objects/3312/3392285/blb1801.html
Atmosphere: vertical motion
http://www.hurricanescience.org/
Heat of condensation 540 cal/g →Heating high troposphere→ augmented air convection Warm ocean &Wind-induced evaporation
Wind-driven oceanic circulation
Northern hemisphere: clockwise, like Gulf stream, California Southern hemisphere anti-clockwise: Chile (Humboldt), Kalahari)
antyzegar
Interdisciplinary search
• You will find the other rocks lie lower, but they are so close together that there is not more than a bowshot between them. [A large fig tree in full leaf grows upon it], and under it lies the sucking whirlpool of Charybdis. Three times in the dayThree times in the day does she vomit forth her waters, and three times she sucks them down againthree times she sucks them down again; see that you be not there when she is sucking, for if you are, Neptune himself could not save you; you must hug the Scylla side and drive ship by as fast as you can, for you
had better lose six men than your whole crew
Homer, Ulysses
In-between Scilla and Charybdis
http://dydaktyka.fizyka.umk.pl/Publikacje_2014/GwSzk1_2014.pdf
Messina Strait
http://it.wikipedia.org/wiki/Stretto_di_MessinaFontanna Herona, Fala w misce w przewężeniu
3 times a day!
A bigger wave: tsunami
http://crisisreliefjapan.files.wordpress.com/2011/10/tsunami-wave.jpghttp://cksimpsonwx.blogspot.com/2013/03/throwback-tohoku-earthquake-and-tsunami.html
Geophysics cardinal points
• Earth’s age: 4,567 mln yrs• Moon: 1/4 of Earth’s diameter• Shape: almost spherical 1/297 ± 100m• Tectonics: colliding every some 300 mln yrs• Cryosphere: bistable system, ~40k yrs• Atmosphere: Coriolis force + 7 days synoptic
Fourier component• Oceans: wind-driven (clock or anti-clock)• Significant human impact