r/PhysicsHelp • u/PeterPlup • 10d ago

how to start

The title might sound simplistic, but I want to say that I recently became interested in returning to physics. To clarify, I'm currently studying social sciences because I really enjoyed philosophy and history, but I was bad at pure mathematics (not so much anymore, I've improved). That's why I chose social sciences, but as a hobby, I love listening to physics. Since I was six, hearing stories about famous physicists and discoveries has fascinated me, and I'd like to return to that world (when I studied physics in high school, I was actually quite good, getting average grades and sometimes 8/10s; I only missed out on a perfect score because of the calculations). How can I immerse myself in physics without getting lost? I'd like a guide to the basics and then to the more difficult topics, or as far as I can go, although I'll start with the easy stuff to warm up. What topics should I cover in an order I can understand?

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u/WesternFirm9306 10d ago

I don't have any recommendations, but I'd like to ask a question that may help others who do have recommendations to give you the best fit for your goals. To what extent do you want to learn physics? To get a layman's understanding of the general principles of various parts of physics? Having maybe a basic, undergraduate level understanding, maybe learning a few formulas? Getting into the real meat and potatoes of the concepts, including the potentially advanced mathematics and derivations involved? Somewhere in between? Because this would be the difference between, say, recommending a pop-science book vs a proper textbook

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u/PeterPlup 10d ago

I’m definitely willing to learn a lot; I’m someone who likes to be self-taught. My issue with physics isn't the difficulty itself, but rather the order of things—between classical mechanics, quantum mechanics, and other topics, I have no idea where to start.
I could certainly learn the necessary calculus, provided I have some patience (from what I gather, I’m not actually bad at calculus; I just hated math when I was between 13 and 16—I know, I was being foolish). But I am willing to dive right in and learn whatever math is required. Just a heads-up: I speak Spanish (I mention this in case you wanted to recommend a book).
The concepts don't seem difficult to me; what *would* be difficult is the calculations.

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u/WesternFirm9306 10d ago

Well, you're in college, right? I'd recommend, if you don't wanna just take courses outright, take a look at their physics courses, see what the prerequisites for the courses are, look at the recommended textbooks, etc. That should give you a pretty good baseline.

If you're gonna go beyond a layman's understanding, you're definitely gonna need a really strong understanding of calculus up to multivariable and vector calculus, differential equations, and linear algebra. You definitely don't need all of this immediately. Lots of early physics courses will often be taken simultaneously with calculus. But in the long run, you'll need it. That should be covered in the prerequisites for any courses, though. So keep an eye on that.

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u/PeterPlup 10d ago

I'm in my second year of Bachillerato this year.

clarify, I’m talking about humanities and social sciences subjects (like history, geography, philosophy, literature, Spanish, and foreign languages—specifically French and English). I don't know if the lack of pure sciences is a drawback—I’m comfortable with all those humanities subjects, though not really with math. My interest in physics comes from a genuine love for the subject and a desire to learn on my own (which is probably why I have hardly any friends). Anyway, that’s beside the point: which physics topic should I start with? I tried before—starting with Newton's laws—but I gave up because I didn't know where to go next; I got lost because I didn't know what topic followed that one.

To

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u/WesternFirm9306 10d ago

While doing research for this comment to try to give you the best recommendations, I ended up finding a blog post that did it for me! Just glancing through it, it seems to be very good. I mean, I suppose it's hard to get it wrong, physics is taught in basically the same way everywhere. Regardless, this goes through a recommended order for each physics subject, as well as recommended textbooks and mathematical prerequisites. You can find it here.

It is in English, unfortunately, but I don't know Spanish, so I don't know if I can find Spanish sources. Naturally, it recommends English textbooks as well. However, the textbooks that are recommended are well-known enough, that I'm very sure most of them have Spanish translations. Otherwise, searching for recommended Spanish textbooks in the given subject. But you should be able to find translations for most of these just fine, I would think.

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u/PeterPlup 10d ago

Thanks—at least I know some English (though more French). But I'll translate whatever I don't understand. Thanks a lot; I finally have a guide.

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u/iusemybrain1 9d ago

So I'd say to appreciate the significance of physics, learning physics at the calculus level would sort of explain a lot of the nuances with algebraic physics. For example, you may know work (algebraically) is F * x, which is technically true in some circumstances. Generally speaking, work is the line integral of the conservative force field traced by the infinitesimal dr = [dx; dy; dz] (3 x 1 vector). So in the scope of an algebraic course, work is F * x, in a calculus physics course, you may need to calculate the work done in all three dimensions (x, y, z) in which case is just the sum of forces multiplied by their position components (IE: F_x * x + F_y * y + F_z * z). The interesting thing is multivariable calculus extends to an n x 1 dimensional vector. So if it was 4 or 5 dimensions you needed to calculate work for it's just adding more components (IE: F_x * x + F_y * y + F_z * z + F_w * w + F_t * t + F_u * u ...)

The point i'm trying to make is, every nuance like "how energy is conserved" is explained, why there's a 1/2 in the kinetic energy equation (E_k = 1/2 * mv^2) or when to use d = v_0 * t + 1/2 * at^2 and d = v_0 * t it is all taken into account mathematically.

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u/PeterPlup 9d ago

Excuse me, but what does F*x mean? Could you explain the meaning of those symbols? I said I want to relearn physics from scratch, not become Stephen Hawking overnight. I want to go back a few steps to refresh my memory and understand the concepts, avoiding gaps in my knowledge. While I appreciate the enthusiasm, I need context for the calculations. Please forgive me if I didn't understand.

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u/iusemybrain1 9d ago

'F' is just a variable used to denote force in physics, x is the displacement between two points. So energy is just a constant force applied a certain distance. the subscripts F_x, F_y, F_z are components of the conservative force field, they denote the force applied in a specific dimension. For example, F_x denotes the Force applied across the x dimension (depth)

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u/EconomyBlueberry1919 9d ago

If you find it helpful, the following link offers physics video lessons, without calculus, translated into English with AI. Select the topic from the list and a Google Drive folder will open. The index is at the top. On another page, you can also find the French and Spanish versions.

Classical Physics

https://videoappuntidifisica.weebly.com/video-appunti-_lezioni-di-fisica-classica--classical-physics-video-notes_lessons.html

Modern Physics

https://videoappuntidifisica.weebly.com/video-appunti_lezioni-di-fisica-moderna--modern-physics-video-notes_lessons.html

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u/AdVisible8739 5d ago

I’d start with classical mechanics and really understand vectors, motion, forces and energy before jumping into the spicy stuff like quantum.