How to memorize derivation?

Dear Arjun Sharma,

Learn the physics, then you can derive the equations you will need. Part of learning the physics is learning the definitions and part is learning the laws, theories, and hypotheses. If you understand these, you should be able to ACE the next exam.

As a retired practicing physicist, I memorized very few equations. And those I did memorize were memorized through frequent use, not because I set out to memorize anything by rote.

Closer to home, as a Top Contributor in Physics, I've answered a lot of questions about trajectories and projectiles, including max range, height, etc. questions. When I first started answering those questions, I used the fundamental conservation of energy law to derive all the equations needed to find the ranges, heights, times, etc. of a trajectory.

I remembered the law, but not the equations, governing trajectories. It had been a long time since I had done trajectory problems at work. So I forgot the equations. But the law stuck with me as it really is pretty simplistic... energy is neither created not destroyed and the corollary, a closed system retains its total energy throughout. From that alone, I could derive the equations needed to do Answers.

Eventually, I memorized some of the equations that kept popping up in my derivations; like R = (U^2/g) sin(2theta) the so-called range equation. But that resulted because I derived them over and over, not because I set out to memorize them by rote.

And that's the approach you should take when studying for exams. Learn the major points of the physics (e.g., Newton's motion laws, conservation of energy, conservation of momentum). Then... THEN... derive some equations on your own, starting with the physics.... including definitions.

I stress definitions because many Askers ask questions that indicate they have no clue about fundamental definitions in physics. Also, some definitions, when written mathematically can give one a head start in deriving further equations. The math definition of impulse dP = m dV = F dt is a great example of this. This little gem can be used to derive all of Newt's motion equations, which I understand he did on impulse one day. [Sorry.]

One last note... when under stress of a time constrained exam, one cannot derive all the equations because that is too time consuming. But if you start with the basics, the ones that are definitional like the impulse equation, that should be enough equations you might need to memorize by rote, just to save time. But if the exams are take home or have virtually no time constraint, start with the physics and go from there.

Hope this helped you dear...........

All The Best........

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