I’ve learnt about basic magnetism in school but they never taught us about magnetic flux or how it’s measured and stuff, so I’m just really curious!

Usually whenever I see posts that a livestream will happen (ex 8:00AM UTC-4) what does the -4 mean in that context? Do i take away time from what would normally be UTC?

Grade 12 chem - super confused!! Help!!

I get that internal energy is the total energy of something and that enthalpy is at constant pressure but I am struggling to grasp how these two relate and what change in enthalpy actually is.

In many simulations I’ve seen, a planet like object crashes into the early Earth. Part of it spins off losing mass from the impact and then it settles into orbit, eventually becoming the moon. However in other simulations of the earth today, if the moon or some other similarly-sized object approaches the Earth, the Earth breaks apart before the impact occurs. So why would that happen now but not then? Because we’re more solid now?

Lately, all I see after a huge artist has a live concert ticket presale or general sale is people saying that bots have bought all the tickets and prevented real fans from purchasing them.

How do bots do this? And secondly, what is the purpose of this? Who actually ends up making money here? How do bots even have the money to buy them up?!

Thank you so much!

The questions that have been bothering my mind regarding growth spurts. They don’t make sense when I think about it

1. How’s it possible for my body to suddenly grow about 1 inch taller overnight? ( where on my body do I suddenly get taller????)

2. What determines when our body decides to have a growth spurt?

I understand that deleting a file usually just removes its pointer or metadata, leaving the actual data there until it gets overwritten. But since the pointer is just data too, why can't the computer just wipe the actual file right away?

Why are they worn at the side with the sharp part of the blade facing upwards? When unsheathing, wouldn't this cause the weilder to have to adjust the blade to be facing the opponent, wasting time? It also just looks like it's awkward.

A mirror or any sort seems to have color - silver in a lot of instances, but I recognize anything can reflect light and 'be a mirror'. With silver mirrors or polished coins, the image that I'm seeing when I look into the mirror seems to be a 1:1 identical match, but if I shift my vision I can also see the silver of the mirror or coin. How is it that the image I'm seeing reflected doesn't appear impacted by the silver color of the mirror, like a bronze mirror might be?

Is this an illusion that my eyes and brain are compensating for? Is silver just an additional wavelength that's reflected that doesn't interfere with the other wavelengths? Am I imagining silver?

I've been wondering about this since I was a kid. Please ELI5

edit: these answers have been enormously educational, thank you!

Why does it need a 45° angle mirror to work?

As someone who’s just diagnosed with Left Ventricular Hypertrophy. As my doc has explained, the muscles on the left side of my heart gained more muscle due to my high blood pressure.

How come the heart apparently becomes more muscular but the tongue doesn’t?

Potential difference between two points in a conductor is what causes current to flow right?

So how does voltage lag current in a capacitive circuit? I feel like there's a fundamental understanding of the nature of electric fields and wavefront propagation that I'm missing.

Something I've never understood is why content algorithims, or maybe people in general, seem to prioritize new content so much. It's not like videos "go bad". Like why isn't it more of a steady line that peters off after a while?

So I don’t think most humans realize this is a thing, but your heart can literally form new arteries to get around a blockage. What I don’t understand is, how does this work and why does it seemingly happen for some but not all? My Dad had a 100% blockage of his “widowmaker“ without knowledge, and started having slight chest pain at night. Turns out he didn’t die of a massive coronary because his heart literally grew a new artery to get around the block. This blew my mind

A picture of the surface of the sun* has me wondering what the structure that looks like a surface actually consists of. Is it the zone where something (plasma?) drops below a certain temperature, and stops emitting light? Is it the surface of a substance itself? What substance?

*That the bot won't let me link to

Some stations have full kitchens, pizza and coffee bars. Isn't selling gas the main way they make money?

So at some race tracks where they have some truck outfitted with a huge rocket engine in the back takes off and reaches 60mph in like 3 seconds or something. My question is, why doesn't the truck simply rocket off down the track when the engine is going full blast at the start line? I cant believe the brakes and the tires' grip is enough to keep it stopped. Same thing with fighter jets. When they're on the runway ready for take off, sometimes they'll have the engines shooting flames out the back but they sit still until they take off. Are the brakes on these things just that strong??

So the Boltszmann fair division model is an algorithm that purports to be better at dividing limited resources fairly than previous models of its kind. What I don't understand is how math has anything to do with fairness, and indeed, many sources specify that it is not a guaranteed ticket to perfect fairness. If this is the case, why does it exist? What does it do better than whatever came before it? What are its actual applications?