- Hi, my name's Sally Weatherly
and I'm an IB Physics teacher.
This week, I really want to drill down
and talk about the topic of Mechanics.
I'd like to discuss
how important is Mechanics
in your life anyway
and how important is
the topic of Mechanics
in the grand scheme of things
when we're looking at
your IB Physics exams?
Because if you're like me,
you'd like to study strategically,
which means you'd like to be able
to study the most heavily
weighted topics first,
have a really good understanding of those
and then study the least
heavily weighted topics last
because they come further
down your priority list,
knowing that if you study
highly weighted topics first,
you've got a greater chance
of getting those marks.
And this may or may not
come as a surprise to you
but Mechanics is, by far, the
most heavily weighted topic
in your final exams.
It doesn't matter if
you're doing COVID exams
where paper 3 has been omitted,
or if you're just doing normal exams
where paper 3 is there.
Mechanics still features
very, very heavily
in your final-year exams.
Let me give you some numbers here.
So if you're looking at normal exams,
so those are exams that are NOT affected
by the COVID pandemic,
then Mechanics in Standard Level,
I need to check my notes,
makes up about 14.8% of your final mark.
Oh, that is definitely the difference.
That's two grades, isn't it?
That could take you from a 4 to a 6.
So in standard level,
14.8% of your final, final
mark is down to Mechanics.
That's in normal exams.
And for higher level,
because there's more
subjects, it's a bit less
but you're looking at around about 8%.
8% of your final mark
is down to Mechanics.
Now we are living in
odd times at the moment
and the exams in 2021 and in 2022
don't have Paper 3.
That affects the weighting slightly.
So if you are in standard level
and you have your exams
in 2021, then a huge,
I think we're looking at
nearly 18% of your final mark
will be solely down to mechanics.
Wow.
And in higher level, for
those sitting your exams
in 2021 or 2022, check my notes again,
still a significant proportion.
We're looking at around about
11 to 12% of your final mark.
So mechanics is hugely
important when it comes
to the strategy in revising
for IB Physics exams.
Now, you may not be thinking
about those exams yet.
You might be at the very
start of your course
and it's even more important to understand
where mechanics sits in
the overall importance
of IB Physics, early on.
Because you might be learning
mechanics in class right now
and you might just be treating it
as you treat any other topic.
But what you really need
to focus on right now
is really developing your
understanding of mechanics
as you learn it, because
the more you understand now
and the more you work on mechanics now,
the easier it will be for you later.
Before I delve a bit
further into the strategy
and the minutiae of mechanics
in terms of the IB physics exams,
I'd love to just chat a
little bit about how mechanics
affects you in real life.
I'll be honest with you, my
world is largely online now
but I have held jobs, I
have had things in my life
that relied on mechanics.
For example, the other day
I was fitting a new gate
in my garden and this gate
is 900 millimeters wide.
And I had to work out what kind
of hinge to get for my gate.
So I was using mechanics in my garden
to work out what type of hinge to get.
It wasn't that difficult.
If I didn't know mechanics,
I would have got the right hinge anyway
but it was interesting that
my knowledge of mechanics
helped me further that
and helped me understand
that process better.
I've also worked in a couple of jobs
where my knowledge of
mechanics has been pivotal,
in terms of I've worked for
an energy company in Scotland
and my knowledge of mechanics
was important there.
And I worked as a technical
producer at the BBC
throughout my university years
and certainly looking
at mechanics in that job
was really, really important.
If you're ever going to look
at an engineering type job
or anything that involves practical work,
then mechanics is
genuinely quite important
for you going forward in life.
So don't discount mechanics
as something you just
have to learn in class,
think about it as a skill
that you can carry on with you
that will allow you to
make your life easier
if you're putting up a gate,
or more employable, if
you're looking for a job.
Let's go back to the exams again.
So we've talked about how
heavily weighted they are
and we've talked about how I recommend
you spend the majority of your revision
or your mental energy right now
on improving your skills in mechanics
as we go through the course.
But let's drill down a little
bit further into mechanics
and let me just check my notes.
Okay, so mechanics is quite a big topic
and some of it, I think,
is fairly straightforward.
So something like the energy topic
I think is relatively straightforward.
You could sit down with no
prior knowledge of physics
and you can get your head around the idea
of conservation of energy,
work done and power and so on.
That's relatively straightforward,
although the exam questions
for that type of topic
and concept seem to be quite
multi-stepped and advanced.
But you know, put that aside.
I think if you spend a
little bit of time on energy,
you'd be fine.
There are three killer
concepts in mechanics
that do tend to stump
other IB physics students.
These killer concepts are heavily weighted
in terms of how much they're examined.
These three killer concepts
are ones that I would recommend
you focus your energies on.
The first killer concept
is projectile motion
and that's really, the
key to understanding
projectile motion is understanding
the idea of direction and vectors.
The second killer concept
is forces in equilibrium.
So looking at objects in equilibrium,
whether they be at a constant
velocity or stationary
and understanding how
to resolve those forces
into different directions.
And the third killer concept,
I believe that most students
struggle with in mechanics
is the idea of the conservation momentum
and how that relates into impulse
and the change in momentum.
So those three killer
concepts are those that I feel
students struggle with the most,
they're ones that students
approached me on the most
and those are the killer
concepts that, if I were you,
I would spend my time
improving my knowledge of and
improving my understanding of.
Now, there are rookie mistakes
that most students make in mechanics
and the biggest rookie
mistake that you can make
in mechanics is not to draw a diagram.
I know it sounds very
dull drawing a diagram
and it doesn't have to
be a perfect diagram.
It doesn't have to have rulers
and it doesn't have to be drawn to scale.
But if you don't draw
a diagram in mechanics,
you find that your
directions are all mixed up
and directions are key to understanding
vector additions and subtractions.
They're also key to understanding
the situation as a whole,
when you're looking at things
like forces or velocities,
accelerations and so on.
So please don't make this mistake.
Please don't make the mistake
that lots of students make.
Please make sure you draw a diagram
when you approach a mechanics problem.
If it's suitable, if it's suitable.
The data booklet for mechanics
is pretty comprehensive.
It has most things that you need
but there are two equations in mechanics
that are not included in the data booklet
and those two equations, I
feel you need to memorize
because I feel that the are very useful
and they speed up your understanding,
not you're understanding,
they speed up your problem-solving
when you're looking at mechanics problems.
Those two equations are,
one is to do with the idea
of conservation of energy.
So if you're looking at a system,
say perhaps a stone is
suspended in the air
and it falls to the ground,
it initially has
gravitational potential energy
and it converts down to kinetic energy,
that closed system has a total energy
and the equation for the total energy,
for an object in free fall
in a gravitational field,
is the total energy, ET,
equals gravitational potential
energy plus kinetic energy.
Now that's not explicitly stated
anywhere in the data booklet
but I do feel that it's
an important equation
for you to have in your brain
and have in your memory system
to help speed up problem solving.
The second equation is to
do with how we define power
but also how we work out
the power of an object
in terms of the work done.
So when you do work on an object,
what you're effectively doing
is you're transferring energy
from one form to another.
And the power is a
measure of how much energy
is transformed from one to
another, as a unit of time.
So you can say that an equation for power
is power equals work done over time
and that's not explicitly shown
in the data booklet either.
So I would suggest you
note that down somewhere
and try and put that to your memory bank.
Mechanics is fundamental to IB physics
and when you get a very
long mechanics problem
and you really nail it
and you realize that you've
just got 13 to 14 marks
in, you know, a paper
that's worth 60 marks,
it is the best feeling in the world
but it won't come easy to you
because the mechanics problems
in your IB physics
paper will be difficult.
So let's learn this lesson here.
Let's not try a problem and give up.
You're not gonna get
very far by doing that.
You have to try a problem,
realize you've maybe not
got the marks you wanted,
or you didn't quite understand every point
and learn from it and move on, okay?
Learn from it and try again.
You've got to be resilient
when it comes to mechanics problems
and you've got to show a bit of tenacity.
You've got to show that
you've got this desire in you
to get better, because you will.
I promise you will.
Now inside my course, Ace
your IB Physics Exams,
I actually talk you through
the killer concepts,
like projectile motion and
what did we say they were?
Conservation of momentum
and force in equilibrium.
I teach them to you
and I teach them to you at
the beginning of the course,
because do you know what?
They are the most heavily
weighted concepts.
In traditional teaching,
it takes two years to
go through IB physics.
It takes two years because
you maybe only have
three to four hours a
week of contact time,
so you're learning IB physics
for three to four hours a week
from your teacher.
And it takes two years to develop
the problem-solving skills
and the exam techniques skills.
The way I like to do teaching
these days is to do it online
and I like to do it in
a step-by-step method.
I like to say, okay, what's
the most important topic,
most heavily weighted topic?
And out of that topic,
we know it's now topic two, mechanics,
which concepts are
examined more frequently
and let's concentrate on them first.
And that's what happens inside
Ace your IB Physics Exams.
So I now have given you
the rundown of mechanics.
If you want to join Ace
your IB Physics Exams
and learn these concepts from me
and learn the exam technique
in mechanics from me,
as I go through papers and
papers and papers with you,
then I'd love to have you.
If not, please take this advice today
and please put it into practice.
I do care about you.
I do care that you enjoy IB Physics.
I do care that you get good grades.
And I do care that we end up with people
who have an understanding of mechanics
and go out into the real big, bad world
and apply it to make the
world a better place.
And I care that that person will be you.
So I hope that this video
this week has given you
a little bit of an
insight into how to manage
your mechanics revision
to be more effective and get
better grades in the long run.
Okay. I'll see you next week.
Have a great day, bye.
