u/IBphysicsvaibhavsir

Hey everyone,
If you are going through the Rigid Body Mechanics unit in IB Physics HL (or any standard rotational mechanics curriculum), you already know that "ladder leaning against a wall" problems are a classic stumbling block.
These questions test your ability to balance multiple concepts simultaneously, and it is incredibly easy to lose a sign or misplace a pivot point. As a physics educator, I see students consistently get tripped up by the same few issues: choosing the optimal axis of rotation to eliminate unknown forces, correctly identifying the direction of static friction at the base, and setting up the equilibrium equations correctly.
To help clear this up, I've put together a comprehensive video breakdown on the Tesla eduventures channel: Ladder Problems — Complete Mastery | Torque + Rotational Equilibrium | Rigid Body #13.
In this breakdown, we focus heavily on visual intuition. I use detailed step-by-step animations and custom diagrams to show exactly how the forces interact rather than just giving you a wall of algebra.
Here is exactly what we cover:
Translational Equilibrium: Setting up \Sigma F_x = 0 and \Sigma F_y = 0 to relate normal forces and friction.
Rotational Equilibrium: Strategic placement of your pivot point to make the \Sigma \tau = 0 equation as simple as possible.
Limiting Friction: How to solve for the exact minimum angle before the ladder slips (\mu_s).
Step-by-Step Problem Solving: Walking through a full IB HL standard question from setup to the final numerical answer.
Watch the full video here: Ladder Problems — Complete Mastery | Torque + Rotational Equilibrium | IB Physics HL |Rigid Body #13
https://youtu.be/KJ5iydCtNEs
If you have any questions on the specific steps, drop them in the comments below or on the video. Let's get these torque concepts locked down before your exams!

Hello everyone,

I want to share something today
that sits at the intersection
of rotational physics and
one of the most dramatic
natural phenomena on Earth —

The Coriolis Effect and
its role in hurricane formation.

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THE QUESTION —
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Every hurricane in the
Northern Hemisphere spins
counterclockwise.

Every hurricane in the
Southern Hemisphere spins
clockwise.

Same planet.
Same atmosphere.
Same low pressure systems.

Opposite rotation directions.

Why?

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THE PHYSICS —
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Earth rotates from west to east
at approximately 465 meters
per second at the equator —

Decreasing to zero
at the poles.

Any object moving freely
across Earth's surface —
wind, ocean current,
or projectile —

Experiences an apparent
deflection due to this
underlying rotation —

This apparent deflection
is the Coriolis Effect.

In the Northern Hemisphere —
moving objects are deflected
to the RIGHT of their
direction of motion.

In the Southern Hemisphere —
moving objects are deflected
to the LEFT.

When wind rushes inward
toward a low pressure center —
this Coriolis deflection
causes the incoming air
to spiral —

Counterclockwise in
the Northern Hemisphere —
Clockwise in the
Southern Hemisphere.

The result —
the massive rotating spiral
we recognize as a
hurricane, typhoon, or cyclone.

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THE PHYSICS BEHIND
THE DEFLECTION —
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The Coriolis acceleration
is given by —

a_Coriolis = 2v × Ω

Where —
v is the velocity of
the moving object
Ω is Earth's angular
velocity vector

This is a cross product —
which means the resulting
acceleration is always
perpendicular to both
the velocity and
Earth's rotation axis.

At the North Pole —
the deflection is maximum.

At the equator —
the vertical component
of Earth's rotation
relative to the surface
is zero —

So the Coriolis Effect
on horizontal motion
is zero at the equator.

This is why hurricanes
never form at the equator —

There is no Coriolis
deflection to initiate
the spiral rotation.

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THE MYTH WORTH BUSTING —
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One of the most persistent
myths in popular science —

"Water drains counterclockwise
in the Northern Hemisphere
and clockwise in the South
because of the Coriolis Effect."

This is completely false.

The Coriolis Effect only
influences motions on a
scale of hundreds of
kilometers or more.

A sink or toilet basin
is far too small for
the Coriolis Effect
to have any measurable influence —

The direction water drains
in a sink is determined
by the geometry of the basin —
the direction water was
poured in —
and residual momentum —

Not by Earth's rotation.

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REAL WORLD APPLICATIONS
BEYOND HURRICANES —
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The Coriolis Effect influences —

→ Long range artillery and
missile trajectories —
military calculations must
account for Coriolis
deflection for targets
beyond a few kilometers

→ Ocean current patterns —
the great ocean gyres
rotate clockwise in the
Northern Hemisphere and
counterclockwise in the South

→ Trade wind patterns —
the prevailing winds that
enabled global maritime
trade for centuries are
directly caused by
Coriolis deflection of
air flowing from
high to low pressure zones

→ Long distance flight paths —
pilots and navigation systems
account for Coriolis
in trans-oceanic routes

One rotating planet —
infinite physical consequences.

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THE IB PHYSICS CONNECTION —
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For IB Physics HL students —

The Coriolis Effect is a
beautiful real world application
of rotational dynamics —

Connecting angular velocity —
cross product mathematics —
and non-inertial reference frames —

Into one unified physical picture.

Understanding the Coriolis Effect
at a conceptual level demonstrates
exactly the kind of physical
reasoning IB Physics HL
examiners reward —

The ability to take abstract
rotational mechanics concepts —
and explain real observable
phenomena from first principles.

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THE SHORT VIDEO —
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I made a short video
explaining the Coriolis Effect
and its role in hurricane
formation — from the physics
of Earth's rotation to
the spiral dynamics of
large storm systems.

https://youtube.com/shorts/a-Y6OIw2pL0?si=V8JcxV19mF2td\_T\_

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A QUESTION FOR THE COMMUNITY —
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Here is something worth
thinking about —

If you were standing
exactly on the equator —

And fired a projectile
due north —

Would the Coriolis Effect
deflect it east or west —

Or would there be
no deflection at all?

Drop your answer and
reasoning below 👇

I will respond to every
attempt with complete
physical explanation. 🎯

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HAPPY TO DISCUSS —
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If you have any questions
about the Coriolis Effect —
or about any other
rotational physics concept —

Drop them in the comments below.

I read and respond to
every single comment. 🙏

Hey everyone, Vaibhav Sir here. After years of teaching IB Physics, I've noticed a massive trap that examiners love to set in the Rigid Body Mechanics (A.4) section.
When you get a problem with multiple forces, multiple objects, and an unknown variable, just memorizing "net force = 0" and "net torque = 0" isn't enough to secure a Level 7. The biggest mistake students make is misidentifying the point of application and failing to visualize how force couples actually rotate a system.
I just put together a complete masterclass breaking down the most challenging rotational equilibrium problems you'll face. Instead of just reading textbook definitions, we go step-by-step through the actual physics:
Balancing non-uniform torque equations without getting lost in the algebra.
The visual trick to never messing up force couples.
Exactly how to set up your hinge force variables so the math naturally works out.
If you want to stop relying on blind memorization and actually understand the mechanics, you can watch the full breakdown here: https://youtu.be/GDtNvt7qQI4?si=pbgYF5ybCO5cBX4a
(Side note: I am also working on uploading complete, question-by-question walkthroughs of original past papers for the channel—no mock papers, only the real ones—so keep an eye out as exam season gets closer).
Drop a comment if you get stuck on a specific step in the video or have any questions about Rigid Body Dynamics. I’m always happy to help clear up the physics!

Hello IB Physics community,

I want to share something today
that genuinely surprises most
IB Physics students the first
time they encounter it —

And that almost no class or
textbook explains with the
physical depth it deserves.

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THE QUESTION THAT STARTS
EVERYTHING —
━━━━━━━━━━━━━━━━━━━━━━━━

Two forces act on a rigid body.

They are equal in magnitude.
They are opposite in direction.
They are parallel to each other.
They act at different points.

The net force on the body
is therefore zero.

By Newton's First Law —
the body should not accelerate.

But it rotates.

How can a body rotate —
when the net force
acting on it is zero?

If this question confuses you —
you are not alone.

This is the Force Couple —

And it is one of the most
conceptually misunderstood
ideas in all of
Rigid Body Dynamics.

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THE HIDDEN TRUTH —
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Here is the insight that
most classes never teach —

The torque produced by
a Force Couple —

Is identical at every
single point in space.

Choose any point.
Any arbitrary location.
Inside the body.
Outside the body.
At one end.
At the center.

The torque is always
the same value —

τ = F × d

Where d is the perpendicular
distance between the
two forces.

This is not obvious.
This is not intuitive.

And it is exactly what
IB examiners test —

Because it reveals whether
a student truly understands
torque —

Or has simply memorized
the formula τ = r × F
and applied it mechanically.

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THE DIPOLE PROOF —
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The most elegant demonstration
of this property is a
dipole placed in a
uniform electric field —

Positive charge +q experiences
force qE in the field direction.
Negative charge -q experiences
force qE opposite to field direction.

Equal magnitude.
Opposite direction.
Parallel forces.
Different points of application.

A perfect Force Couple —
producing pure rotation —

With torque τ = pE sinθ —

The same at every point
in the field.

This connection between
rotational mechanics and
electrostatics —

Is one of the most
beautiful cross-topic
links in all of
IB Physics HL.

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THE SECOND CONCEPT —
POINT OF APPLICATION —
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The same force —
applied at different
points on the same body —

Produces completely different
physical outcomes.

Applied at the center of mass —
pure translation —
no rotation.

Applied at any other point —
translation AND rotation
simultaneously.

Applied as part of a couple —
pure rotation —
zero translation.

This is the Point of
Application of Force —

And understanding it physically —
not just mathematically —

Is what allows you to
immediately visualize what
will happen to any body
under any force system —

Before writing a single equation.

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WHY THIS MATTERS FOR
IB SPECIFICALLY —
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IB Physics HL topic A.4 —
Rigid Body Dynamics —

Tests this concept in
two different ways —

First — directly in
rotational mechanics questions
asking about couples and
their moments.

Second — indirectly in
electrostatics questions
about dipoles in uniform fields —

Where the student must
recognize that the dipole
is experiencing a Force Couple —
and apply the torque formula
τ = pE sinθ correctly.

Students who learned these
as two separate unconnected topics —
struggle with the
electrostatics questions.

Students who understood
Force Couple deeply —
recognize the connection instantly
and solve both question types
with the same physical reasoning.

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WHAT THE VIDEO COVERS —
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This is Lecture 9 of my
complete Rigid Body Dynamics
playlist for IB Physics HL —
covering topic A.4 of the
IB Physics syllabus.

In this video —

→ Complete definition and
physical understanding
of Force Couple

→ Why net force is zero
yet rotation occurs —
the complete explanation

→ The moment of a couple —
derivation and physical meaning

→ Proof that torque of a couple
is the same at every
arbitrary point —
complete mathematical proof
with physical reasoning

→ Point of Application of Force —
how it changes the
physical outcome completely

→ Complete demonstration using
a dipole in a uniform
electric field —
connecting rotational mechanics
to electrostatics

→ IB exam style problems
on Force Couple and
Point of Application

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THIS IS PART OF A
COMPLETE SERIES —
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This video is Lecture 9 of
my complete Rigid Body
Dynamics playlist —

Which covers IB Physics HL
topic A.4 from absolute zero
to full exam level —

Including —

Lecture 1 — Rigid Body Definition
Lecture 2 — Complete MOI Derivations
Lecture 3 — Parallel Axis Theorem
Lecture 4 — Perpendicular Axis Theorem
Lecture 5 — MOI of Cut Bodies
Lecture 6 — Mass Distribution Property
Lecture 7 — Radius of Gyration
Lecture 8 — Torque Basics
Lecture 9 — Force Couple (this video)

All completely free.
All with full physical reasoning.
All timestamped for easy navigation.

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VIDEO LINK —
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https://youtu.be/JEMsy4xQaT0?si=QdiqBZK6rwzE\_zA4

Timestamps for every section
are in the description —
jump directly to any
concept you need.

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A QUESTION FOR THE COMMUNITY —
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Before watching the video —

Can you answer this?

A Force Couple has a
net force of zero —

Yet it produces a torque.

About which point is
that torque calculated?

A — Only about the center of mass
B — Only about one of the
points of force application
C — About any arbitrary point —
the value is always the same
D — It depends on the
geometry of the body

Drop your answer below 👇

The reasoning behind
the correct answer —
and why the wrong options
are wrong —
is exactly what this
video explains. 🎯

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HAPPY TO HELP —
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If you have any questions
about Force Couple —
Point of Application —
or any concept in
Rigid Body Dynamics —

Drop them here or
in the video comments.

I read and respond to
every single comment. 🙏

Good luck to everyone
preparing for their
upcoming IB exams.

I just uploaded complete solutions
to every question in the
IB Physics HL Paper 1A 2026 TZ1.

I searched YouTube before uploading —
could not find a single complete
solution video for this paper.

So here it is. Every question.
Full explanation. Free.

Whether you just sat the exam
and want to check your answers —
or you are using this for
future exam preparation —

This video covers everything.

Every answer includes —
→ The correct answer clearly stated
→ Complete reasoning explained
→ Why the wrong options
are incorrect
→ Mark scheme approach shown

Timestamps for every question
are in the description —
so you can jump directly
to any question you need.

🔗 https://youtu.be/iBQs3V-OuRo?si=oy22-xRABAzLgFEM

If you found this useful —
please share it with every
IB Physics student you know.

Drop any questions about
specific questions in
the comments below —
I respond to everything. 🙏

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 —
━━━━━━━━━━━━━━━━━━━━━━━━

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

━━━━━━━━━━━━━━━━━━━━━━━━
THE GOLDEN RULE I TEACH
MY STUDENTS —
━━━━━━━━━━━━━━━━━━━━━━━━

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 —
━━━━━━━━━━━━━━━━━━━━━━━━

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.

━━━━━━━━━━━━━━━━━━━━━━━━
VIDEO LINK —
━━━━━━━━━━━━━━━━━━━━━━━━

🔗 https://youtu.be/2lKSqmMaL9w?si=-NjqXq8pwQz5XhGt

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 —
━━━━━━━━━━━━━━━━━━━━━━━━

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. 🙏

━━━━━━━━━━━━━━━━━━━━━━━━
FINAL THOUGHT —
━━━━━━━━━━━━━━━━━━━━━━━━

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. 🎯

Hello IB Physics community,

I want to share something I have
been building over the past few weeks —

A complete, structured, lecture-by-lecture
playlist on Rigid Body Dynamics —
specifically built for IB Physics HL.

I am Vaibhav Agrawal — a Physics educator
with 16 years of teaching experience at
Allen, Aakash, Resonance and Sri Chaitanya.

I trained thousands of students for
JEE Advanced — one of the most demanding
Physics examinations in the world.

Now I am bringing that same depth of
conceptual teaching to IB Physics HL.

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WHY I BUILT THIS PLAYLIST —
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After speaking with hundreds of
IB Physics students over the past year —

The single most common complaint
I heard about Rigid Body Dynamics was —

"I memorized all the formulas —
but I still cannot solve
the exam problems correctly."

That complaint has one root cause.

Most resources teach the WHAT.

Nobody teaches the WHY.

Why does the Parallel Axis Theorem
have the form it does?

Why does the Perpendicular Axis
Theorem ONLY work for 2D laminas?

Why does removing a symmetric part
from a body not change the
structural form of the MOI formula?

These are the questions that
determine whether a student
scores a 5 or a 7 in IB Physics.

This playlist answers all of them.

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WHAT THE PLAYLIST COVERS —
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Lecture 1 —
Definition of Rigid Body Systems
+ Is any body permanently rigid?
+ Rotational Kinematics basics
+ 4 numerical problems

Lecture 2 —
Complete Moment of Inertia —
All standard derivations from scratch
Ring, Disc, Sphere, Cylinder,
Cone, Rod, Rectangular Lamina,
Cuboid, Cube — every single one
derived step by step

Lecture 3 —
Parallel Axis Theorem —
The physical significance most
classes never explain —
Why a body rotating about a
non-central axis performs TWO
simultaneous motions —
Complete derivation + problems

Lecture 4 —
Perpendicular Axis Theorem —
2 conditions most students
never learn —
Why it ONLY works for 2D laminas —
Why axes can intersect OUTSIDE
the body and theorem still holds —
Complete derivation + problems

Lecture 5 —
MOI of Cut Bodies —
Partial disc, sphere with cavity,
frustum — the principle that
makes all cut body problems
immediately solvable

Lecture 6 —
Mass Distribution Property —
Why removing a symmetric part
preserves the MOI formula structure —
The deepest conceptual insight
in the entire chapter

Lecture 7 —
Radius of Gyration —
What K = √(I/M) physically means —
not just the formula —
PLUS MOI of a rod inclined
at angle θ to the axis

Lecture 8 —
9 Challenging MOI Problems —
Medium to IB exam level —
All solved step by step with
complete physical reasoning —
Pause and attempt each one
before watching the solution

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WHAT MAKES THIS DIFFERENT —
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Every lecture in this playlist
is built around one principle —

Physical reasoning first.
Mathematics second.

When you understand the physics
behind every formula —
you stop needing to memorize.

You start being able to derive
and reconstruct from first principles —

Which is exactly what IB Physics
Higher Level examinations reward.

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A NOTE ON DIFFICULTY —
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I want to be honest about
what this playlist is and
what it is not.

This is NOT a quick revision
resource for the night before
your exam.

This is a complete, structured
learning system for students
who want to genuinely master
Rigid Body Dynamics —

Built for students who are
willing to pause, attempt,
and think — not just watch.

If that is you —
this playlist was built
specifically for you.

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COMPLETELY FREE —
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Every lecture in this playlist
is completely free.

No subscription.
No paywall.
No hidden anything.

Just Physics — explained properly.

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PLAYLIST LINK —
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🔗 https://youtube.com/playlist?list=PLPwT3DpMmxCEFY0SXqKwIi1fKaacH6Gyz&si=LnQlykqyJ0IHjMVi

Each lecture has full timestamps
in the description — so you can
jump directly to any concept
without watching the entire video.

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WHAT IS COMING NEXT —
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The playlist is still growing.

Upcoming lectures will cover —

→ Torque and Angular Momentum
→ Rotational Kinetic Energy
→ Rolling Motion — pure and
with slipping
→ Angular Impulse
→ IB Past Paper problems on
Rigid Body Dynamics — solved
→ Conservation of Angular Momentum

New lectures drop every week.

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ONE LAST THING —
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If you are an IB Physics student
who has been struggling with
Rigid Body Dynamics —

I want you to know something.

This chapter is NOT as difficult
as it feels when it is taught
as a collection of formulas.

It is actually one of the most
elegant and satisfying chapters
in all of Physics —

When the physical reasoning
is built correctly from the ground up.

That is exactly what I have tried
to do in this playlist.

I genuinely hope it helps. 🙏

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HAPPY TO HELP —
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If you have any questions about
any concept in Rigid Body Dynamics —
or about any specific lecture —

Drop them in the comments here
or on the video itself.

I read and respond to every
single comment.

Good luck to everyone preparing
for their upcoming exams. 🙏

Hello IB Physics community,

I want to share a problem with
you today that genuinely made
several of my brightest students
stop and think for a long time —

Before the beautiful moment of
understanding finally arrived.

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THE PROBLEM —
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A ring of mass M sits
on a flat ground surface.

Two small balls each of mass m
are placed at the top of the ring
and released simultaneously.

They slide down the smooth
inside surface of the ring.

The velocity of each ball
at any point is given by —

V = √2gh

where h is the height dropped
from the starting position.

The height of points A and B
from the bottom of the ring
is h = R/2 —

meaning points A and B are
located at 60 degrees from
the vertical on each side.

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THE QUESTION —
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For what value of the ratio m/M —

Will the ring just lift off
the ground —

Meaning the Normal reaction
force on the ring from the
ground becomes exactly ZERO —

At the exact moment the balls
reach points A and B?

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BEFORE YOU SOLVE —
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I want to ask you something
more fundamental first.

Most students when they
see this problem —
immediately reach for
their formula sheet.

But before any calculation —
can you physically explain
WHY the ring would lift off
the ground at all?

What is the physical mechanism
that creates an upward force
on the ring?

Where does that upward force
come from?

Answering that question
conceptually first —

Is what separates a student
who gets the right answer
by luck —

From a student who truly
understands the physics.

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KEY CONCEPTS INVOLVED —
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This problem beautifully
combines —

→ Circular motion of the
balls inside the ring

→ Newton's Third Law —
the reaction force that
balls exert on the ring

→ Resolution of forces —
finding the vertical component
of the reaction force at
points A and B

→ Condition for liftoff —
Normal force from ground
equals zero

→ Force balance on the
complete system

Each concept on its own
is straightforward.

The beauty of this problem
is how they all work together
simultaneously.

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WHY THIS TYPE OF PROBLEM
MATTERS FOR IB —
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IB Physics examiners —
especially at Higher Level —

Do not just test whether
you can apply a formula.

They test whether you can —

→ Identify which physical
principles are relevant

→ Set up the problem correctly
from first principles

→ Apply Newton's Laws to
a non-obvious situation

→ Reach a clean algebraic
result with correct reasoning

This problem tests all four
of those skills simultaneously.

If you can solve this confidently —
and more importantly explain
the physical reasoning clearly —

You are thinking at the level
IB examiners reward with 7s.

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A HINT IF YOU NEED IT —
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Do not read this if you
want to attempt it first.

.
.
.
.
.

Hint —

At points A and B —
each ball is moving in
a circular path.

The centripetal force required
for that circular motion —
must be provided by the
Normal force from the ring
on the ball.

By Newton's Third Law —
the ball exerts an equal
and opposite force on the ring.

Find the vertical component
of that force at points A and B.

Then apply force balance
to the entire system vertically.

Set Normal force from ground
equal to zero.

Solve for m/M.

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MY SHORT ON THIS PROBLEM —
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I posted a complete solution
Short on my IB Physics channel —

Where I walk through the
physical reasoning and
complete solution step by step.

🔗 This Ring FLIES on its Own?! 🤯 #IBPhysics #shorts
https://youtube.com/shorts/4b1OzlggxNk?feature=share

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DROP YOUR ANSWER BELOW —
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I genuinely want to see
how the community approaches this.

Tell me —

→ What is your value of m/M?

→ More importantly —
what was your physical
reasoning before you
started calculating?

→ Which step did you
find most challenging?

I read and respond to
every single comment.

If you get stuck on any step —
ask specifically where
you are stuck —

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

Good luck! 🎯

[FREE RESOURCE] IB Physics HL — Rigid Body
Dynamics Lecture 1 | Complete Introduction,
Definition & Rotational Kinematics Solved

Hello IB Physics community,

I am an experienced Physics educator
with 16 years of teaching experience
at some of India's largest coaching
institutions.

I recently launched a dedicated YouTube
channel — IB Physics with Vaibhav Sir —
specifically built for IB Physics HL
students worldwide.

Today I am sharing the first lecture
of my complete Rigid Body Dynamics
playlist — and I want to start with
something that most students and even
many teachers get wrong.

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THE QUESTION I ASK MY STUDENTS —
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"Can you give me the scientifically
correct definition of a Rigid Body System?"

Most students answer —

"A rigid body is an object that
does not deform or change shape."

That answer sounds reasonable.

But it is NOT the definition an
IB examiner expects from a 7 scorer.

The correct definition is —

A Rigid Body System is a system of
particles in which the distance between
every pair of particles remains absolutely
constant — regardless of the external
force applied on it.

The distinction matters enormously
in IB Physics — because the examiner
is not testing your memory.

They are testing your depth
of understanding.

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AND HERE IS THE DEEPER QUESTION —
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Can the same body behave as a
Rigid Body in one situation —
and as a Non Rigid Body
in another situation?

Think about it carefully
before reading further.

The answer is — Yes. Absolutely.

A rubber ball rolling smoothly
on a flat surface behaves as
a Rigid Body —
because inter-particle distances
remain essentially constant.

The same rubber ball hitting a wall
deforms on impact —
inter-particle distances change —
it behaves as a Non Rigid Body.

Same object. Same system.
Two completely different behaviors —
depending entirely on the situation.

This is why in Physics we never say
an object IS a rigid body.

We say it BEHAVES as a rigid body
under specific conditions.

This single conceptual clarity can
change how you approach multiple
questions in your IB exam.

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WHAT THIS VIDEO COVERS —
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This is Lecture 1 of the complete
Rigid Body Dynamics playlist
for IB Physics HL.

In this video —

→ Complete topic sequence of the
entire Rigid Body Dynamics chapter

→ Scientifically correct definition
of a Rigid Body System

→ Is any body permanently rigid? —
Physical reasoning with examples

→ Example problems on Rigid Body
definition

→ Complete comparison of Rotational
Kinematics vs Linear Motion

→ 4 fully solved numerical problems
on Rotational Kinematics —
worked step by step

Everything is explained with
physical reasoning —
not just formula application.

Because understanding WHY
is what separates a 6 from a 7
in IB Physics.

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WHO THIS IS FOR —
━━━━━━━━━━━━━━━━━━━━━━━━

→ IB Physics HL students
currently studying this chapter

→ Students who found Rigid Body
Dynamics confusing in class

→ Students preparing for
May 2026 or November 2026 exams

→ Anyone who wants to build
genuine conceptual clarity —
not just exam technique

━━━━━━━━━━━━━━━━━━━━━━━━
VIDEO LINK —
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🔗 Rigid body dynamics |scientific definition of Rigid body |Rotational kinematics |IB physics
https://youtu.be/1lNHPUFBJ9c

Timestamps are in the description
so you can jump directly to any
section you need.

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ONE LAST THING —
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I genuinely believe that every
IB Physics student deserves access
to clear, deep, and honest
Physics teaching —

Regardless of where they are
in the world.

That is exactly what this
playlist is built to deliver.

If you have any questions about
any concept covered in the video —
drop them in the comments here
or on the video itself.

I read and respond to every comment.

Good luck to everyone preparing
for their upcoming exams. 🙏