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k a May Highlights and 2025 AoPS Online Class Information

jlacosta 0

May 1, 2025

May is an exciting month! National MATHCOUNTS is the second week of May in Washington D.C. and our Founder, Richard Rusczyk will be presenting a seminar, Preparing Strong Math Students for College and Careers, on May 11th.

Are you interested in working towards MATHCOUNTS and don’t know where to start? We have you covered! If you have taken Prealgebra, then you are ready for MATHCOUNTS/AMC 8 Basics. Already aiming for State or National MATHCOUNTS and harder AMC 8 problems? Then our MATHCOUNTS/AMC 8 Advanced course is for you.

Summer camps are starting next month at the Virtual Campus in math and language arts that are 2 - to 4 - weeks in duration. Spaces are still available - don’t miss your chance to have an enriching summer experience. There are middle and high school competition math camps as well as Math Beasts camps that review key topics coupled with fun explorations covering areas such as graph theory (Math Beasts Camp 6), cryptography (Math Beasts Camp 7-8), and topology (Math Beasts Camp 8-9)!

Be sure to mark your calendars for the following upcoming events:
[list][*]May 9th, 4:30pm PT/7:30pm ET, Casework 2: Overwhelming Evidence — A Text Adventure, a game where participants will work together to navigate the map, solve puzzles, and win! All are welcome.
[*]May 19th, 4:30pm PT/7:30pm ET, What's Next After Beast Academy?, designed for students finishing Beast Academy and ready for Prealgebra 1.
[*]May 20th, 4:00pm PT/7:00pm ET, Mathcamp 2025 Qualifying Quiz Part 1 Math Jam, Problems 1 to 4, join the Canada/USA Mathcamp staff for this exciting Math Jam, where they discuss solutions to Problems 1 to 4 of the 2025 Mathcamp Qualifying Quiz!
[*]May 21st, 4:00pm PT/7:00pm ET, Mathcamp 2025 Qualifying Quiz Part 2 Math Jam, Problems 5 and 6, Canada/USA Mathcamp staff will discuss solutions to Problems 5 and 6 of the 2025 Mathcamp Qualifying Quiz![/list]
Our full course list for upcoming classes is below:
All classes run 7:30pm-8:45pm ET/4:30pm - 5:45pm PT unless otherwise noted.

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0 replies

jlacosta

May 1, 2025

0 replies

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i A Comprehensive List of Physics Olympiad Resources

Lol_man000 177

N Aug 13, 2024 by enya_yurself

A Comprehensive List of Physics Olympiad Resources

Before I start, I would advise everyone to read this link for lots of advice on starting and learning physics.

Updates

Introductory Physics Books
[list]
[*] Physics by Halliday Resnick Krane (Calculus-based) Harder version of HRW with about 1/3 more harder material added to each chapter. Previous editions were edited by former USAPhO coach. This book covers almost all the material required for physics olympiads and is recommended by many coaches and teachers alike.
[*] Fundamentals of Physics by Halliday Resnick Walker (Calculus-based). Easier version of Halliday Resnick Krane (HRK, see above).
[*] Physics: Principles with Applications by Giancoli (Algebra-based)
[*]Physics for Scientists and Engineers by Randall D. Knight (Calculus-based).
[*] University Physics by Young. Similar to HRK, it covers a lot of the first year undergraduate sequence and contains loads of information.
[/list]

Subject Specific Books
[list]
[*] An Introduction to Classical Mechanics by David Morin. Comment (USAPhO/IPhO, some chapters are relevant to F=ma practice)

[*] Electricity and Magnetism by Purcell and Morin. Comment (USAPhO/IPhO)

[*] Introduction to Electrodynamics by David J. Griffiths. Comment (USAPhO/IPhO)

[*] Concepts in Thermal Physics by Stephen J. Blundell, Katherine M. Blundell. Comment (USAPhO/IPhO, some chapters are too high level for IPhO)

[*] An Introduction to Mechanics by Kleppner and Kolenkow. (USAPhO/IPhO, some chapters are relevant to F=ma practice). Comment

[*] Vibrations and Waves by A.P French. Comment (USAPhO/IPhO, some chapters are too high level for IPhO)

[*] Thermal Physics by Daniel Schroeder. (USAPhO/IPhO, some chapters are too high level for IPhO) Comment

[*] Modern Physics by Kenneth S. Krane
[/list]
Problem Books/Handouts
[list]
[*] Problems and Solutions in Introductory Mechanics by David Morin (A good book for preparing to the F=ma exam and for practicing basic mechanics)
[*] 200 More Puzzling Physics Problems by Peter Gnadig.
[*] Pathfinder for Olympiad & JEE:Physics by Arwind Tiwari/Sachin Singh. Comment
[*] Problems in General Physics by I.E Irodov.
[*] Jaan Kalda's Handouts by Jaan Kalda (F=ma to IPhO Level Problems) (solutions are found here)
[*] Physics Olympiad - Basic to Advanced Exercises by The Committee Of Japan Physics Olympiad Japan
[*] Competitive Physics: Mechanics and Waves by Wang and Ricardo
[*] Competitive Physics: Thermodynamics, Electromagnetism and Relativity by Wang and Ricardo.
[*] Thinking Physics by Lewis Carroll Epstein (a book of conceptual problems for beginners and intermediate-levels)
[*] 200 Puzzling Physics Problems by Gnadig (USAPhO / IPhO level problems)
[*] Aptitude Test Problems in Physics by S.S Krotov.
[*] 300 Creative Physics Problems with Solutions by Holics (USAPhO / IPhO level problems)
[*] Physics to a Degree by Thomas and Raine (USAPhO / IPhO level problems)
[*] Thinking Like a Physicist by Thompson (USAPhO / IPhO level problems)
[*] F=ma Solutions Manual by Branislav Kisacanin and Eric K. Zhang.
[*] Feynman's Lectures on Physics.
[*] 1000 Solved Physics Problems by Kamal
[/list]

List of Physics Contests
[list]
[*] IPhO Comment
[*] EuPhO Comment
[*] F=ma Exam Comment
[*] USAPhO Comment
[*] Physics Bowl Comment
[*] BAUPC Comment
[*] Pan Pearl River Delta Physics Olympiad Comment
[*] HKPhO
[*] NBPhO
[*] IZhO
[*] Physics Cup Comment
[*] OPhO Comment
[*] Sir Isaac Newton Exam
[*] FYKOS Internet Physics Competition
[*] INPhO
[*] APhO
[*] BPhO
[*] AuPhO
[*] Princeton University Physics Competition
[*] Gulf Physics Olympiad
[*] Online Physics Brawl
[*] PUEC
[*] JPhO (in Japanese)
[*] SwissPhO
[*] Moscow City Physics Olympiad (In Russian)
[*] MIPT (Fiztekh) Physics Olympiad (In Russian)
[*] Saint Petersburg Physics Olympiad (In Russian)
[*] Belarusian Physics Olympiad (In Russian)
[*] EstPhO (in Estonian)
[*] Eötvös Competition (in Hungarian)
[*] Fizika
[*] The University Physics Competition
[*] Rudolf Ortvay Competition in Physics
[*] ThWorldCup
[/list]

Other Resources
[list]
[*] Kevin Zhou's Olympiad Handouts Comment
[*] Physics Olympiad Hub Comment
[*] Everaise Academy Physics Classes Comment
[*] Physics WOOT created by AoPS.
[*] F=ma Problem Series Class created by AoPS.
[*] PhysOlymp
[*] KöMaL Magazine (in Hungarian)
[*] Quantum Magazine.
[*] Physics Genie
[*] Upgrade Your Physics by BPhO.
[*] MIT OCW 8.01 (Classical Mechanics)
[*] MIT OCW 8.02 (Electricity and Magnetism)
[*] MIT OCW 8.03 (Vibrations and Waves/Optics)
[*] AwesomeMath Physics Classes.
[*] Isaac Physics.
[*] Physics Stack Exchange
[*] AoPS Physics Forums :P
[/list]

Summer Camps & Other Opportunities (In progress)
[list]
[*] If you are interested in doing research, consider looking at summer programs offered by your local universities! Many offer one and you can have an internship working with a professor over the entire summer and potentially during the school year as well. If not, cold emailing is also a great option.
[*] Summer Science Program (SSP)
[*] Research Science Institute (RSI)
[*] Quantum School for Young Students (QSYS)
[*] International Summer School for Young Physicists (ISSYP)
[*] Boston University RISE
[*] Summer Program on Applied Rationality and Cognition (SPARC)
[*] High School Honors Science, Math and Engineering Program (HSHP)
[*] University of Florida Student Science Training Program
[*] Texas Tech Clark Scholar Program
[*] Center for Astrophysics, Space Physics & Engineering Research (CASPER)
[*] Yale Summer Program in Astrophysics
[*] MIT Introduction to Technology, Engineering, and Science (MITES)
[*] Garcia Summer Program
[*] George Mason University Aspiring Scientists Summer Internship Program (ASSIP)
[*] Note: I would shy away from "pre-collegiate" summer programs at prestigious universities that have you pay because they are typically a grab for money (6-7k+) and don't really teach you very much (also they admit most students that apply). They don't look that great for a college application either.
[/list]

177 replies

Lol_man000

May 9, 2020

enya_yurself

Aug 13, 2024

J

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Applying momentum conservation

ARYANMATHS 4

N 4 hours ago by millburnmathfan

I am not to figure out whats exactly happening ..plz help me out

4 replies

ARYANMATHS

Sep 25, 2020

millburnmathfan

4 hours ago

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2015 F=MA Problem 2

millburnmathfan 0

4 hours ago

I just tried to solve F=MA 2015 problem 2, and I had some doubts. For reference, the problem is:

A car travels directly north on a straight highway at a constant speed of 80 km/hr for a distance
of 25 km. The car then continues directly north at a constant speed of 50 km/hr for a distance of
75 more kilometers. The average speed of the car for the entire journey is closest to
(A) 55.2 km/hr
(B) 57.5 km/hr
(C) 65 km/hr
(D) 69.6 km/hr
(E) 72.5 km/hr

My solution was that the car traveled total 100 kilometers and it traveled at 80 km/hr for 25% of the journey while it traveled at 50 km/hr for 75% of the journey. In this case couldn't one just take the weighted average and do 0.25x80+0.75x50? Here, 0.25x80+0.75x50 gives us 57.5, which is answer choice B. However, the correct answer to this problem was A (55.2 km/hr). Can someone explain to me how to solve this problem and where did I go wrong in my solution?

Thanks

0 replies

millburnmathfan

4 hours ago

0 replies

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Special USAPhO

neeyakkid23 0

Today at 12:46 AM

Is it possible to make a special request to take the USAPhO without having permanent residency? Asking for a friend btw

0 replies

neeyakkid23

Today at 12:46 AM

0 replies

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Physics Paradox

Riptide1901 6

N Yesterday at 6:37 PM by whoosh

Two identical small masses each of mass $m$ are connected by a light inextensible string on a smooth horizontal floor. A constant force $F$ is applied at the mid point of the string as shown in figure. Find the acceleration of each mass towards each other. The string is originally strait and taught.

I'm confused of a paradox that seems to emerge. When you apply the force, $F=ma$ implies that there should be a net acceleration of the CM of the system in the direction of the force. But at the same time, the tension can only apply forces on each mass towards one another (perpendicular to the direction of the force). So how is it possible that the CM of the masses accelerate in the direction of the force?

6 replies

Riptide1901

May 22, 2025

whoosh

Yesterday at 6:37 PM

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Question USAPhO

Riptide1901 2

N Yesterday at 6:19 PM by ForeverSnow

I'm confused about part (b) of Problem A2 from the 2025 USAPhO.

If the mass of the gas is $m_g$ then the black hole would pull on the gas with a force of $\frac{GMm_g}{(R-r)^2}$ while the star would pull on the gas with a force $\frac{Gmm_g}{r^2}$ in the opposite direction.

So wouldn't the tidal acceleration be
$\frac{GM}{(R-r)^2}-\frac{Gm}{r^2}$ instead of
$\frac{GM}{(R-r)^2}-\frac{GM}{R^2}\,?$

2 replies

Riptide1901

Yesterday at 5:19 PM

ForeverSnow

Yesterday at 6:19 PM

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A Little Help Needed

Saucepan_man02 3

N Yesterday at 3:18 AM by naonaoaz

I was going through this handout link. In Idea 5 of Section, I didnt quiet get what the statement meant. It was mentioned that it was proved in M2 handout (or Griffiths Problem 1.62), but I didnt quiet "get" the concept from either.

Could anyone kindly explain (it will be very helpful if the explanation is comprehensive and detailed) the "Idea 5" of the handout?
Thanks in advance...!

3 replies

Saucepan_man02

May 20, 2025

naonaoaz

Yesterday at 3:18 AM

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An Electrostatic Problem

Saucepan_man02 1

N May 22, 2025 by Riptide1901

Could anyone solve the below problem in an elegant way?

Like I did solve it using Mathematica (by equating electric field to 0), but then, I believe this problem has an elegant method.

Answer

1 reply

Saucepan_man02

May 21, 2025

Riptide1901

May 22, 2025

J

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An Electrostatic Challange

Saucepan_man02 2

N May 21, 2025 by Saucepan_man02

Here is the problem: link. Could any explain what's going in this question (a rough diagram is appreciated if possible)? I am unable to visualise the diagram properly.

Source

2 replies

Saucepan_man02

May 21, 2025

Saucepan_man02

May 21, 2025

J

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Why does perpetual motion imply lack of energy conservation, if it does?

club52 1

N May 20, 2025 by BelowAverageAsian

Recently I have been trying to understand why perpetual motion machines are impossible. The argument that most people make is that it is clear that perpetual motion machines are impossible, since generating work without an energy source violates conservation of energy. I agree with the latter statement fully, however it does not follow for me that a perpetual motion machine is impossible. I think the implication of the argument is that a perpetual motion machine would necessitate a free energy source. However, nowhere have I found an explanation for why this is the case.

Here is a very simple design for a perpetual motion machine. Fire a projectile of mass $m$ . Now, sit and wait. If you do this in deep space, it should go on forever in a straight line (classically). I know that the energy of the object will eventually be lost to the curvature of spacetime, but that is besides the point.

I have also heard that perpetual motion machines are not allowed by the first law of thermodynamics; however the law appears to me to be simply a restatement of the law of conservation of energy. Again, I can't see why all motion must stop without an external energy source.

1 reply

club52

May 20, 2025

BelowAverageAsian

May 20, 2025

J

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Doubt in Electrostatics

Saucepan_man02 6

N May 18, 2025 by whoosh

Suppose we place a point charge $q$ (not at the center of sphere) inside a hollow conducting sphere. Will it face a non-zero force due to the surface of the sphere?

I think it should be non-zero, though in some places its claimed to have net zero force:
link.
This problem is also discussed in Purcell & Morin (Problem 3.6), where it tells the force to be non-zero.

6 replies

Saucepan_man02

May 13, 2025

whoosh

May 18, 2025

J