Fuck It, Its Self Indulgence Saturday. Anakin Skywalker, But He Was Raised On Mandalore, And Also His

Tehran, Iran (2014)

'Giant Saucer Stones' Landscape Feature, Boulsworth Hill, Briercliffe, Lancashire.

Mars

Raging Bear Creek Falls by Andrew Morse

Orbit change of artificial satellite

In order to raise the altitude of an artificial satellite, it is necessary to accelerate it. When the orbital speed increases, the centrifugal force generated by the rotation of the satellite becomes stronger than the gravity of the earth applied to it, then the altitude rises. At this time, a certain amount of energy is returned from the satellite to the vacuum space to reduce the energy debt. Hence the orbital speed decreases and finally drops below the initial speed. The sum of the reduced amount of the momentum energy and the energy required for the acceleration is returned to the vacuum space.

In order to lower the altitude of an artificial satellite, it is necessary to decelerate it. When the orbital speed decreases, the centrifugal force becomes weaker than the gravity, then the altitude drops. At this time, the satellite is given a certain amount of energy from the vacuum space. Hence the orbital speed increases and finally rises above the initial speed. The sum of the increased amount of the momentum energy and the energy released by the deceleration is borrowed from the vacuum space.

1,000 Years of Scientific Texts From The Islamic World Are Now Online

Between the 9th and 19th centuries, Arabic-speaking scholars translated Greek, Latin and even Sanskrit texts on topics such as medicine, mathematics and astronomy, fostering a vibrant scientific culture within the Islamic world.

The library, a joint project of the British Library and the Qatar Foundation, offers free access to 25,000 pages of medieval Islamic manuscripts. Among some of the most significant texts:

The Book of Knowledge of Ingenious Mechanical Devices (1206 A.D.), which was inspired by an earlier, 9th-century translation of Archimedes’ writings on water clocks. Devices such as the “Elephant Clock” were the most accurate time-keeping pieces before the first pendulum clocks were built in the 17th century by the Dutch scientist Christiaan Huygens.

This is one of the only three recorded copies of an influential treatise on the construction and use of astrolabes by Abū al-Rayḥān Muḥammad ibn Aḥmad al-Bīrūnī (973-1048), containing 122 diagrams.

See more manuscripts at the Qatar Digital Library.

[via io9]

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Hi! Can you tell some uni or colleges math resources?

Can you be more specific? Like resources for studying for particular undergrad level classes?

A few “classic” online references:

Paul’s online math notes (https://tutorial.math.lamar.edu/): algebra, calc 1-3, diff eqs though I’ve mostly only used the calc ones. A common favorite

Khan Academy: haven’t actually used any of their math stuff for years but I remember their videos were good

3blue1brown: he has a series on calc, diff eqs, and linear alg. I haven’t actually watched many of these either but his videos are generally good and I know people who like the series in particular

If you mean higher level math, I tend to just use a search engine and end up referencing a mix of wikipedia, wolfram mathworld, random pdfs from various universities, and math stack exchange. And of course textbook pdfs

If you give me more details, I’ll see if I can think of anything else!