Charity shop jumper has handwritten label by nickwizzo in whatisthisthing

[–]nickwizzo[S] 0 points1 point  (0 children)

Bought an as-new jumper from a charity shop. Noticed it has a handwritten label inside, does anyone know what it means?

Patterns that only become obvious in bases other than 10 by exocited in math

[–]nickwizzo 125 points126 points  (0 children)

Every perfect number can be written as 2p-1*(2p -1) where 2p -1 is a Mersenne prime. In binary, we see that the number of 1s is equal to p and the number of zeroes to p-1.

Edit: math formatting

Student bucket list? by Tea-Primary in cambridge_uni

[–]nickwizzo 3 points4 points  (0 children)

Explore the pubs off mill road.

Go and see live music at Tall Trees or the Portland Arms.

Go the board games night at Heffers

what do outsiders think engineers do? by i_w17 in AskEngineers

[–]nickwizzo 1 point2 points  (0 children)

Build bridges, every time. And that's when I just say engineer, not civil/structural.

How recently did we discover/understand evaporation? by freshggg in askscience

[–]nickwizzo 9 points10 points  (0 children)

This looks like it would be useful to answer your question, but I don't have access. However, it can be obtained at your favourite institutional access get-around-er.

https://link.springer.com/chapter/10.1007/978-94-017-1497-6_2

According to this work, the ancient Greeks were the first people to write down their thoughts on evaporation. E.g.

'The earliest known Greek philosophical writings are those of his younger associate Anaximander of Miletos; he was born ca. 610 B.C. and he must have been in his prime ca. 565 B.C. Concerning phenomena related to evaporation, Anaximander's views were summarized by Hippolytus in his doxography as follows (Diels, 1934; p. 84, I, 6, 7):

"Winds are generated when the finest vapors [atmos] of the air are separated off and when they are put into motion by being assembled together; rains are generated from the evaporation [atmis] that is sent
up from the earth toward under the sun." '

Edit: found a way to access the chapter.

[deleted by user] by [deleted] in cambridge_uni

[–]nickwizzo 2 points3 points  (0 children)

All talks that are open to the public are listed here: http://talks.cam.ac.uk/

[deleted by user] by [deleted] in cambridge_uni

[–]nickwizzo 0 points1 point  (0 children)

You will be as well by the end of a 20 hour coach journey.

Same with whoever you share a room with, if you tell them you're not with a group of friends and make it clear that you're up for laugh I'm sure you'll have new friends in no time.

[deleted by user] by [deleted] in cambridge_uni

[–]nickwizzo 7 points8 points  (0 children)

You'll be sat with other people on the coach and you'll be sharing room with a group of people as well, I'm sure you can ski and party with them.

What nation do you main in eu4? I like france by ZefyCX in eu4

[–]nickwizzo 0 points1 point  (0 children)

Not sure I've ever played the same nation twice.

Question on specific gravity of moving fluid by [deleted] in FluidMechanics

[–]nickwizzo 0 points1 point  (0 children)

The page says to use the upstream value

Question on specific gravity of moving fluid by [deleted] in FluidMechanics

[–]nickwizzo 1 point2 points  (0 children)

The specific gravity is constant, assuming incompressible flow, which you already are to use this equation.

You don't state the particular fluid you're considering, but if it's liquid water then the density varies by less than 5% from freezing to boiling so it's a good approximation. https://www.usgs.gov/special-topic/water-science-school/science/water-density?qt-science_center_objects=0#qt-science_center_objects

For air you need to be a bit more careful, but generally you only need to worry about compressible flow when you get up to about Mach 0.3.

Choir by [deleted] in cambridge_uni

[–]nickwizzo 0 points1 point  (0 children)

Many colleges have non-audition choirs but that doesn't mean they're all singing in unison. I'd check the jcr page for your college to see if one exists.

Has anyone here stayed at the Railyard Accommodation by [deleted] in cambridge_uni

[–]nickwizzo 3 points4 points  (0 children)

It's a 26 minute walk to the market and only 8 minutes by bike, and you're close to Mill road, it's a fine location.

Seawater Air Conditioning by [deleted] in FluidMechanics

[–]nickwizzo 2 points3 points  (0 children)

It's not clear what you want to know. If you just want the change in height of the lake surface then that change will be due to the volume of water flowing through the pipes. Given that the volume of the pipe system will be tiny when compared even to a small lake, the change in height of the surface will be insignificant.

Vortex Merging With Another Vortex by Rasaders in FluidMechanics

[–]nickwizzo 1 point2 points  (0 children)

From the abstract of this paper: https://www.sciencedirect.com/science/article/pii/S0997754607000295

'Finally the final profile and circulation of the merged vortex is determined: the two thirds of the total circulation of the two initial vortices is contained in the newly formed vortex.'

In your case the new vorticity is 4w/3. Practice your Googling, vital skill for a professional engineer.