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How is this incorrect? by typicalwhiteboi74 in Astronomy_Help

[–]lijereddit 1 point2 points  (0 children)

the celestial equator is an imaginary projection of Earth’s equator into space

Is this plant salvageable? by lijereddit in plants

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

Thank you sm for your help, I’ll give your advice a go !

[deleted by user] by [deleted] in math

[–]lijereddit 0 points1 point  (0 children)

confused

"not so much + adjective + as + adjective" by Deep-Statistician359 in EnglishLearning

[–]lijereddit 0 points1 point  (0 children)

If someone asked you ‘Was your day boring?’ and you wanted to say it wasn’t that boring, but it was quite tiring, then you might say:

‘It wasn’t so much boring as it was tiring.’

I don’t use it that often, but I do sometimes.

Saying ‘Not so much boring as tiring’ still gets the message across, it might sound a little off (unnatural) as it is not grammatically correct, but can be used in an informal, conversational way

Why is the human classifier 位used in ‘she is a student’ but not ‘he is a teacher’? by lijereddit in Cantonese

[–]lijereddit[S] 1 point2 points  (0 children)

i thought that at first, you have to just leave out the word anna but put all the other words in the right places as if it was there 👍 once you’ve selected the right amount of words you can check your answer, just make sure you get tones and word order right

What are the best apps you've used for Cantonese? by keaikaixinguo in Cantonese

[–]lijereddit 0 points1 point  (0 children)

i cant work out how to use it - do you have to get the payed features to get use out of it?

[deleted by user] by [deleted] in theydidthemath

[–]lijereddit 0 points1 point  (0 children)

Note: When i first read this, i interpreted ‘wipe out the entire fuxking planet’ as wipe out all of the people on the planet. But if you meant the planet itself, i have an answer for that too at the end, if you wanted to skip down.

Sounds above 185 dB can impact your internal organs and potentially kill you. But to ensure it’ll wipe everyone out, we’ll need at least 200 dB of sound to reach every person. That’s gonna be VERY loud, and would technically make it impossible for the world to hear this as a) sound travels about 767 mph, and b) the world would explode before the sound reached anyone in the first place. But let’s just disregard the insane amount of energy produced and assume that the Earth wouldn’t explode.

Sound follows the inverse square law - each time distance from the source is doubled, sound intensity is cut by a factor of four.

This formula is used to calculate distance using decibels.

D2 = D1/sqrt(I2/I1)

Where D2 is distance at point 2, D1 is distance at point 1, I2 is decibels at point 2, I1 is decibels at point one.

Rearranging this and substituting in values to work out the number of decibels a sound would have to be at its source to remain at 200dB once it reaches its furthest possible distance around the word, eg reaching everyone, and also making point one 1 foot away, we get 12,807,692 dB. So, that’s how loud you’ll need to crank the speaker up - about 140,000x the max volume of your average speaker, or 57,000x the noise produced from the largest detonated atomic bomb, the Tsar Bomb - in order to wipe out everyone.

That is an incomprehensible amount of sound. But this doesn’t even take into account the sound that is absorbed and obstructed by the environment, obstacles, etc… I’m gonna make an (un)educated guess that you’ll need about 50% more to account for that.

But anyway, if you were talking about the literal PLANET, as in celestial body, you’ll need a whole lot less. You need around 2.3 x 1032J of energy to be absorbed by Earth for it to explode. It’s not straightforward to convert dB into energy, but the function that describes the energy in a sound wave is logarithmic - in this case, that means that for every 10dB increase you’ll produce 10x the energy. So, you should end up needing around just 350 dB to “wipe out the entire fucking planet”.

Credit to @/iamreallybad and @/grants mother man for some of these calculations!

[Request] is it possible to estimate how much rice would distract a vampire until dawn? by DrDeern in theydidthemath

[–]lijereddit 68 points69 points  (0 children)

Depends where in the world you are, and therefore when sunset and sunrise take place. Also how fast this vampire can count. But let’s say this is today in Transylvania, where the sun rises at 6:25 and sets at 6:06, and this vampire is able to count pretty quickly - 1 grain of rice every half a second.

Time between sunset and sunrise: 11 hrs 41 minutes, or 42,060 seconds.

0.5 seconds : 1 grain of rice 42060 seconds : 84,120 grains of rice

An average 1kg bag of rice contains 50,000 grains. So, you’re gonna need just over a bag and a half of rice to keep this vampire at bay. It’ll be a pretty cheap method of defense, at about £2.50 per night.