Shoemaker (formerly Teague) Impact Structure

"The Shoemaker (formerly Teague) Impact Structure—located in Western Australia in a drainage basin south of the Waldburg Range—presents an other-worldly appearance in this astronaut photograph. The Shoemaker impact site is approximately 30 kilometers (19 miles) in diameter and clearly defined by concentric ring structures formed in sedimentary rocks (brown to dark brown, image center). The rocks were deformed by the impact event approximately 1.63 billion years ago (as reported by the Earth Impact Database). Other age-dating analyses of granitic rocks at the core of the structure call this age into question (Pirajno et al. 2003)."
http://eol.jsc.nasa.gov/EarthObservatory/Shoemaker_Impact_Structure.htm
"Beginning with the Mercury missions in the early 1960s, astronauts have taken photographs of the Earth. Our database tracks the locations, supporting data, and digital images for these photographs. We process images coming down from the International Space Station on a daily basis and add them to the 1,101,059 views of the Earth already made accessible on our website."

Biofuel for flights

"Lufthansa, Europe's second-largest airline, became the first carrier in the world to offer regular scheduled flights running on biofuel, with four daily round trips between Hamburg and Frankfurt.
The airline will use a biofuel blend using 50 per cent so- called hydrotreated renewable jet fuel, Lufthansa said. The fuel is made from feedstocks including inedible plants and wood chips. Lufthansa will fly an Airbus A321 on the services." Read more
http://www.smh.com.au/travel/travel-news/lufthansa-begins-worlds-first-regular-biofuel-flights-20110718-1hks1.html

La portata

Testo e immagini adattate da 

Halliday Resnick Walker

Fondamenti di Fisica

Millikan's experiment

Testo e immagine adattati da

Halliday - Resnick - Crane

Fisica II

Dipolo

Un dipolo elettrico è un sistema composto da due cariche elettriche uguali e opposte di segno. È uno dei più semplici sistemi di cariche che si possano studiare e rappresenta inoltre l'approssimazione basilare del campo generato da un insieme di cariche globalmente neutro tramite lo sviluppo in multipoli di quest'ultimo.

Immagini adattate dal libro

Halliday, Resnick, Krane, Fisica 2

n.14 - Esercizio - elettrostatica

Volcanoes under Antarctic waters

"Scientists from British Antarctic Survey (BAS) have discovered previously unknown volcanoes in the ocean waters around the remote South Sandwich Islands. Using ship-borne sea-floor mapping technology during research cruises onboard the RRS James Clark Ross, the scientists found 12 volcanoes beneath the sea surface — some up to 3km high. They found 5km diameter craters left by collapsing volcanoes and 7 active volcanoes visible above the sea as a chain of islands."
More http://www.antarctica.ac.uk/press/press_releases/press_release.php?id=1541

An acoustic superlens from a few cans of cola

""Acoustic metamaterial" may sound exotic, but researchers in France have managed to assemble one from a few multipacks of cola cans. Arranged in a grid, the drinks cans act as a superlens for sound, focusing acoustic waves into much smaller regions than their metre-long wavelengths typically allow. The cans act as resonators, directing the volume of the sound to peak in a space just a few centimetres wide, and this heightened precision could improve acoustic-actuator systems."

How to make a superlens from a few cans of cola - physicsworld.com

n.13 - due piani carichi

Two infinite sheets of  electric charges with uniform densities intersect at right angles. The plane of the figure is perpendicular to the planes. Let us suppose that changes cannot move.
a) Find the magnitude and direction  of the electric field everywhere and sketch the lines of the field, in the case that a sheet has positive density (+sigma) and the other an equal but negative density (-sigma).
b) find the magnitude and direction of the electric  field everywhere and sketch the lines of the field, in the case that the two sheets have the same densitity with the same positive sign, + sigma.
c) Find the difference of potential V(A)-V(B), between the point A and B placed at a distance d on a line in the plane of the figure at 45° with respect to the charged planes.

n.12 - una piccola sfera