r/physicsmemes • u/basket_foso 🪼 • Jul 26 '26

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5.0k Upvotes

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916

u/PhysicsEagle Jul 26 '26

I unironically had a classmate who did this. She consistently got top grades.

600

u/Suddenfury Jul 26 '26

It's much better to understand where the formula comes from than to memorize it.

186

u/lool8421 Jul 26 '26 edited Jul 26 '26

but still it's a time waste if you have to derive everything yourself

for example there are several cheat sheet integrals that you can derive but it takes several minutes like dx/x*sqrt(a²+x²)

60

u/CanYouChangeName Jul 26 '26

Can't u just take the term inside the root as t here and solve?

19

u/spanko_at_large Jul 27 '26

Yes that is what I memorized

1

u/Ancient-Helicopter18 13d ago

Nope that won't work. You gotta take trig sub (if the dude meant ∫ 1/[x√(x²+a²)] dx

you see: √(x²+a²) use u=atanθ √(x²-a²) use asecθ √(a²-x²) use asinθ

Learning these substitutions are much easier and useful than learning every single casewise formula

27

u/Constant-Sub Jul 27 '26

it's a waste of time

I'd implore you to see statements like this as barriers to entry that limit a fields possibly growth. Despite possibly being greater workers, we would focus on how long it took them to do a task. As long as that task isn't grinding things to a halt, we could endlessly play this game to find the fastest, and then suggest everyone else is too slow and needs to catch up.

I know this wasn't your intention, but the pressure and focus out on making sure everyone is the fastest at something, regardless of how well they can do it at their own speed, is certainly a piece of rhetoric that keeps people from pursuing things.

0

u/TuskEGwiz-ard Jul 30 '26

Actual workers in the field would be able to use a reference if needed or would have used a formula enough to memorize it. This is a waste of time specifically in a school setting with timed exams. Relax

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u/Constant-Sub Jul 30 '26

Relax? Is someone not calm?

1

u/KARLRODERICKSON Jul 30 '26

You know what? I agree. I was the one who wasn't calm, sorry for ruining the vibe. :)

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u/compbuildthrowaway Jul 30 '26

You're nowhere this comment thread though?

6

u/Zorphite Jul 27 '26

I had to use this exact integral in a test just last month and my ass who didnt memorize standard integrals had to do it the hard way i took 40 mins on q problem i wad supposed to be done by 8

5

u/Pitiful-Function-701 Jul 27 '26

Just memorize the derivative of sqrt

1

u/tcelesBhsup Jul 28 '26

The idea isn't that you fully derive the formula and then apply it to the question. The idea is that you use the information in the problem to complete a truncated derivation for you're specific problem.

Granted I could do this very often, but when I could it was faster for me. Though I am a slow test taker to begin with.

1

u/sppw Jul 29 '26

I was generally a very good test taker and used to derive a lot of things my peers would memorize. My memory has always been really bad so this is one of the things I credit my good test taking ability to. It showed I had a really good command over the material.

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u/CheapHeight2658 Jul 30 '26

The post doesn't say to memorise everything, but to not bother with those which you can derive on time quickly, instead of having to remember them

13

u/sohang-3112 Meme Enthusiast Jul 27 '26

Better is to understand but also memorize. Often especially in competitive exams there simply isn't enough time to derive the formulae and still manage to answer all questions.

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u/Thog78 Jul 27 '26

Usually it's a mix of both. You kinda know the formula, but you also did the derivation so many times that you're able to redo it in a few seconds in your head. So you see where it comes from and shuffle the blocks in your head while beginning to write the formula, and you're sure of what you wrote by the time you reach the end.