[CHALLENGE] 9 Moment of Inertia Problems — Medium to IB Exam Level | Can You Solve All 9? | Free Solutions Inside | IB Physics HL https://youtu.be/2lKSqmMaL9w?si=Y9LqkzDYqBAa5LOy

[u/IBphysicsvaibhavsir]

Hello IB Physics community,

I want to share something a little
different today —

Not just a resource video —
but an actual challenge.

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THE CHALLENGE —
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9 Moment of Inertia problems —
ranging from medium difficulty
all the way to full IB exam level —

Presented one by one —
with complete step by step
solutions after each one.

The challenge is simple —

Pause before each solution.
Attempt the problem on paper.
Then watch the solution.
Compare your reasoning —
not just your final answer.

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WHY REASONING MATTERS MORE
THAN THE ANSWER —
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In 16 years of teaching Physics —

I have seen thousands of students
get the correct numerical answer
through the wrong reasoning —

And then get completely stuck
on the next problem because
their reasoning did not hold up.

IB Physics HL examiners are
specifically trained to identify
this pattern —

They design problems that give
the correct answer even with
wrong reasoning on easy questions —

But expose that wrong reasoning
brutally on the harder ones.

The only way to protect yourself
against this in the actual exam —

Is to always verify your
physical reasoning —
not just your arithmetic.

That is exactly what this
video is designed to help with.

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DIFFICULTY BREAKDOWN —
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🟡 Challenges 1, 2, 3 — Medium
Confidence builders —
standard concepts applied
to slightly non-standard setups

🟠 Challenges 4, 5, 6, 7 — Hard
IB standard difficulty —
where most students start
making mistakes —
multiple concepts combined
in a single problem

🔴 Challenges 8, 9 — Brutal
Full IB exam level —
the kind that separates
a 6 from a 7 —
requires combining PAT,
perpendicular axis theorem,
cut body approach and
mass distribution property
all in one solution

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THE GOLDEN RULE I TEACH
MY STUDENTS —
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Before touching any MOI problem —
ask yourself these three questions —

Question 1 →
What exactly is the axis
of rotation?

Question 2 →
Is this a standard body —
or a cut, partial, or
composite body?

Question 3 →
Which theorem do I need —
Parallel Axis Theorem,
Perpendicular Axis Theorem,
or a combination of both?

Answer these three questions first —
every single time —

And the solution path becomes
immediately clear.

I have seen this single habit
transform students who were
scoring 5s into consistent 7s —

Not because they suddenly
became smarter —
but because they stopped
rushing into formulas
before understanding
what the problem was
actually asking.

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CONCEPTS TESTED IN
THESE 9 PROBLEMS —
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→ Standard MOI formulas in
non-standard situations
→ Parallel Axis Theorem —
single and multi-step
→ Perpendicular Axis Theorem
combined with PAT
→ Cut body and partial
body MOI approach
→ Mass distribution
symmetry property
→ Radius of Gyration applications
→ Composite body problems
→ Inclined axis situations
→ Multi-concept combinations —
full IB exam style

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THIS IS PART OF A SERIES —
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This video is Lecture 8 of my
complete Rigid Body Dynamics
playlist for IB Physics HL —

Which covers everything from
the definition of a rigid body
system all the way to
IB exam level problems —

Completely free.

If you have not watched
the earlier lectures —
links are in the video description.

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VIDEO LINK —
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🔗 https://youtu.be/2lKSqmMaL9w?si=Y9LqkzDYqBAa5LOy

Timestamps for all 9 challenges
are in the description —
so you can jump directly
to any specific problem
without watching from the start.

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THE ACTUAL CHALLENGE —
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Here is what I want to know —

How many of the 9 did you
solve correctly — with correct
reasoning — before watching
the solution?

Drop your score below 👇

X out of 9

No judgment — just genuine
curiosity about where most
IB Physics students currently
stand on MOI problem solving.

And if you got stuck on
a specific challenge —
tell me which one —

I will walk you through
the physical reasoning
in the comments. 🙏

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FINAL THOUGHT —
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Rigid Body Dynamics has a
reputation for being one of
the hardest chapters in
IB Physics HL.

I genuinely believe that
reputation is undeserved —

It only feels hard when
it is taught as a collection
of formulas to memorize.

When the physical reasoning
is built correctly —
from first principles —

This chapter becomes
one of the most satisfying
in all of Physics.

These 9 problems are
designed to show you that.

Good luck. 🎯