- 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.