I did 2d motion problems and dynamics. the 2d motions were mainly projectiles, there were two projectiles on inclines, and also optimizations. The dynamic problems focused a lot on constrained motion and conservation of string and these complex atwood machines which are a pain to do.

My initial plan was to finish HRK before summer and finish Morin by the end of summer. The school year just ended and I was barely halfway done with the book. In addition, I felt that HRK problems are mostly straight forward and the challenging problems often focus too much on math and not physics. Morin is universally known as one of the best competition physics textbooks. Although HRK is also known to be a good book, its reputation is no where near that of Morin’s. I had originally not wanted to start Morin because, knowing it’s a challenging book, I wanted to focus more on my fundamentals. Not only that, last December, while I was studying on vacation, I remember spending hours trying to solve Morin free-response problems only to find myself getting nowhere. However, given the timeline and the kinds of problem I was looking at, I decided to start Morin. So I did 1d motion, projectile problems and optimizations, and some non- uniform circular motion. There were some projectile on incline problems which I struggled with and am gonna come back to later and some calc based problems cause I do now know what a taylor series is yet.

I did systems of many particles and variable mass systems. I learned finding center of mass with integrals and interactions with variable mass so like snow falling on train or rockets, and derived the tsiolkovsky rocket equation. The variable mass systems reminded me of this old problem of snow falling on a train. I remember being stumped and struggling to work it out, and one day at school when I was bored, I finally solved it on a table with a white board marker. Although the solution I found was not too complicated, it is a bit challenging to think of. The calculus approach, instead, is actually more intuitive and allows you to solve it mentally.

I worked on more collision problems, these were more about things hitting each other and not falling things. There was also this question of a cat jumping back and forth two moving sleds and it was challenging for me because it uses a lot of relative velocity stuff and the number of collisions. there was a gravity assist problem which is really easy if you know the elastic collision assumption. and then theres this problem on a ball hitting two target balls at the same time. This was actually on the 2025 f=ma questions 2-3 which I did not solve. I unfortunately did not solve this even though ive seen it like 3 months ago. But it was cause I only tried to use momentum and I really had to use both momentum and energy so Im not sure why energy straight up did not come to my mind. maybe it was all the problems I did before were more momentum and impulse based and I just forgot energy existed. then theres this really hard problem asking to prove something about the deflection angle. Theres this solution by feynman lectures that i think is really genius in how it uses the center mass frame, i havent fully understood it yet so ill still be learning it

I worked on collision problems, many had the use of non constant forces, like a chain falling onto a scale, or marbles dropping into a box, hail stones at a certain frequency falling, or whatever other collisions. I couldn’t solve the chain one myself, so I spent a while studying the solution. But I got another similar problem right, so hope that means I understand it. Variable mass systems are actually very interesting to me, especially how they deviate from the typical high school physics problems.

I worked on the momentum problem and this textbook teaches most things in the cm frame and not lab frame. Concerningly, I just learned that momentum in cm frame is always zero. And the derivation for final velocities under elastic collisions is sooo much faster and less work in the cm frame than the lab frame. Supposedly collison problems are much easier in the cm frame so I hope that’s true. This topic, might genuinely be my weakest cause on past f=ma exams I struggled with it

Note: When I was studying on a cruise last year during Thanksgiving break, I remember trying to derive the equations for final velocities in elastic collision and I ended up with nearly two pages of very messy work—an abomination of energy and momentum equations, which got extremely messy with all the squares. The typical collision problems I have done in school and non-competitive resources usually give you the final velocity of at least one, and the starting of both. In some setups, however, only the initial velocities are given.

Note: After learning some cm frame tricks, the final velocities in elastic problems have become significantly easier.

From now on, I’m gonna be documenting weekly instead of every study session. Ive been busy with some school work,but I have been studying. These past weeks I finished the forces problems in the textbook. There were some questions with interesting setups that I was shaky on so I’ll do again sometime. There was one problem of proving the angle at which a plumb bob (like a long pendulum) hangs from. This problem was interesting because it shows how the Earth’s rotation causes big objects, like the pendulum, to hang at an angle instead of being perfectly straight. I initially tried to use coriolis and non-inertial frames to solve. This did not work, of course, because coriolis affect only exists for objects moving with non zero velocity relative to Earth. The actual solution uses a simple force setup and relations with period of the Earth (using Kepler’s). The most challenging part was actually the setup because it required a lot of geometry and vector decompositions. I also learned the derivation for the capstan equation which was pretty cool.

Note: I do not think I ever went back to those problems.

I worked on more free responses in 2d motion and also some drag problems and also derived functions of velocity and acceleration with time under drag forces which were really long. Not too much done.

I did the chapter on 2d and 3d motion, which included relative vectors, drag forces, circular motion and the derivation of centripetal acceleration—which was pretty straightforward. The centripetal acceleration uses the “small-slice” technique where you consider an infinitesimal portion of a circle, a commonly used technique in physics derivations. I then did the multiple-choice questions, and started some free-responses the setups were pretty unconventional which made great practice.

I took a three week break because the school marking period was ending and I had to lock in on my exams. I started the forces chapter and found the explanations of fictitious forces and inertial and non-inertial frames to be well-written. I have been reading the actual text of the book, which I normally do not, and I’ve also never been advised to do so. But looking back, there were some concepts that, if I had read earlier, could have avoided some conceptual misunderstandings. Some past f=ma questions used similar concepts and I would have been better off knowing them. The multiple-choice questions in this textbook were really straight forward and I did not find them to be very valuable. I also finished about half the free responses—which too, were decently straight forward, excluding the exception of some math-heavy problems.

Note: Taking that three week break was honestly unnecessary and did not improve my academic performance in school. Now that I think of it, my olympiad physics studying may have been continuously improving my thinking ability and intellectual capability. From now on, I will try to fit in physics studying even if I’m busy with school work.

I reattempted the last questions and there’s still one problem I can’t solve and ended up writing a long proof that didn’t work. But I finished the rest of free responses and I checked my answers and re-did the problems I got wrong. There’s still one or two problems I’m not sure of so I’ll have to go look at them. This topic also annoys me cause it’s almost never ideal to solve problems with kinematics unless necessary. Usually energy is the go-to strategy, and then dynamics, and I’m assuming, worst case, kinematics.

I Continued to work on 1d and 2d motion free-response questions. I thought I would have finished but the last four stumped me — some questions are very math and calculus heavy. Not too much done.

I started studying at 5 : 40 am today because I have lots of work later on in the day. I worked more on HRK free response kinematic questions. I feel slow, but I’m not gonna rush since I heard the later chapters build a lot on earlier intuition. I’ve recently been so bogged down with other competitions and school work, so I’ll try to learn as much as I can in the morning.

I started studying at 10 and was already tired so I should’ve started earlier. I finished the 1d motion multiple-choice questions and then started working on free-response questions. I noticably struggled; and it was concerning to see myself struggle at some, what should be, simple problems. Or, I could have been a bit brain-dead. One thing I have noticed is that I’m slow at adjusting to unfamiliar problem types — which could definitely be an obstacle to competitive problems.

I just did the F=ma exam and honestly, I knew how to do about five out of the twenty-five questions. I haven’t practiced with recent exams but just doing pre-2020 exams I have typically scored below thirteen. I have one more year so I have to seriously lock in. I’m taking a break from past exams for a while because I’ve unfortunately done most of them and remembered a lot of answers, which will hinder my practice. In addition, if I have serious underlying issues, it would be more beneficial for me to improve my basics first. So I started on the first chapter of Halliday Resnick Krane textbook. This feels like going back to square one since im reviewing the concepts I first learned. But, it is very important for my fundamentals to be strong. So I derived kinematic equations and did some calc based kinematic questions.

One major difference between this textbook and how I first learned physics is that this one is calculus-based. Before learning physics, I had not learned calculus; so naturally, I learned physics the algebra way. Reading the lectures made me realize that physics should not be taught with algebra. Every physical quantity is a derivative or integral of another. The basic kinematic formulas, what I initially struggled to memorize, were only simple differential equations. Algebra-based physics, how I first learned, is nonetheless stuffing formulas and memorization with no meaning nor understanding.