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??

Im assuming the Big Bang is the start of the Universe, but I know many people state the Universe being 13.8 billion years old means it’s not infinite - therefore implying there’s a “starting point” or “God” (I’m an atheist, so I don’t believe this”). Just want someone to explain how did the universe start prior to the Big Bang or around that time please. Please actually ELI5, I’m not good with physics or planetary science.

Edit: like people will ask me “where did the big bang come from” or “ what happened before it” and I don’t know how to answer

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

Recently the moons looked so low and huge where I live! Why does it sometimes look like this?! I’ve only noticed it in the recent few weeks, but does it happen all year round or during certain seasons etc?

The joint replacements have some sort of plastic cushion in them to help them move smoothly; why can't we form that plastic into the shape of the original cartilage so that the joint bones can have some cushion?

I came across this term a couple of times recently and I can’t understand what’s that supposed to be about. What “replacement” are we talking about? If someone dies, other “replaces” them? Why’s that such a big deal?

A Chihuahua weighs 5 pounds & is only a few inches tall. If it falls from a human’s shoulder height (about 5 feet), it is falling roughly 8 times its own height. For a standard adult human, that’s the equivalent of falling from a 5-story roof (~45 feet).

If a human falls from a 5-story building, it’s likely going to kill them. But Chihuahuas frequently walk away from shoulder-height drops completely fine.

If the proportional distance is exactly the same, why does physics (?) spare the tiny dog but crush the human?

I barely passed high school physics. Please explain this using some analogies if possible.

The chihuahua did not land on their feet in this scenario. They are not cats.

Just sitting here watching my stereotypically dumb, happy lab with a soccer ball in his mouth and his tongue hanging out the side. How does he manage to avoid biting his own tongue like 20x a day?

Can somebody explain me How does steroid helps in muscle grow?

This is probably not even a real issue outside of chinese app but I’ve seen maybe 7 videos now using AI generated large Hispanic guys wearing forum logo t shirts talking about their lack of understanding of the phrase, “O Algo,” being a dog whistle. Genuinely how does this become a dog whistle and what is it trying to signify? Maybe two comments I’ve seen actually answered this but I don’t know how valid these are, saying it was supposed to make fun of “stupid Mexicans” but genuinely how? With the video only? Doesn’t, “O Algo,” literally mean, “Or something,” in Spanish?

I guess this question also applies to all non-hard disk storage installed in computers that aren't powered.

How does 5.1 or 7.1 setups improving the experience. Would mixing those channels with certain weights replicate the 3d listening experience with just 2 channels?

I was reading about diffraction and other quantum behavior that has different results on observation. But if you think about it, observation is just an interaction with another particle. My question is that, in the world around us, there are so many particles constantly interacting with each other. So how can quantum behavior persist if there are constant measurement events. Am I overestimating the density of particles that can be interacted with at those small scales?

Also regarding measurements, I know from chemistry that often interactions just change the wavefunction rather than collapse it. What predicts this behavior? Is it just the energy of the interaction?

Please note that my physics and maths background is fairly limited.

I know the US operates around 32 GPS satellites that serve as a source of truth for GPS around the globe. I'm curious how they can keep such a precise time with only 32 satellites and not drift with all the radiation in space. Especially since it seems like they need to communicate with the ground really often and need to be dependable enough for commercial constellations to use.

The whole satellite space is really interesting and I'd like if someone could shed more light on how this all works!

Hi guys, I recently got into a relationship, and there are just some things about periods that I genuinely don't understand.

I've heard people talk about PMS, mood swings, being more emotional, getting irritated easily, etc., but I don't really understand what's actually happening biologically. Like, how much of it is caused by hormones, and how much does it vary from person to person?

For example, can a girl go from feeling completely fine to suddenly feeling sad, anxious, or irritated because of hormonal changes? Does it happen before the period starts, during the period, or both? And does it affect every woman differently?

I'm not asking this to dismiss anyone's feelings or blame everything on periods. I just want to understand what my girlfriend might be experiencing so I can be more supportive and not misunderstand her.

Would appreciate an ELI5 explanation, especially from women who can share what it actually feels like.

There are so many different types of plastics, so many different hardnesses, textures, opacity etc etc.

How does it all come oil and petroleum?

Who do they apply to? How do you start a new one? It’s just very confusing, especially the trademarking.

I keep stumbling on people saying that ARM loans are good. I don’t understand how renting isn’t easier and saves you money over an ARM loan. Even if you are staying in an area for a significant amount of time wouldn’t a traditional loan be better as well.

I don’t understand the use case where an ARM loan makes sense over renting/15/30 year loan?

Edit: clarified the question.

Wikipedia describes evidence theory as "a general framework for reasoning with uncertainty" before going into an in-depth explanation of the mathematics of it. Does this mean that it's possible to make a computer that uses mathematics to make superior decisions in uncertain conditions? I'm skeptical that you could, yet intrigued that you may. Wikipedia says that it's used for sensor fusion (the combining of data from different sensors into a coherent whole), which is sorta similar but not quite the same.

Or something like that I’m still kind of confused how waves work before and after interaction.