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For 2019 the rules around the minimum allowed
weight are changing slightly. This year, the
total weight of the car and driver together
would have to weigh at least 733 kg excluding
fuel
Next year, the driver and their seat must
meet a minimum weight on their own. It’s
expected this will be 80 kg. The rest of the
car, excluding fuel will have to make up the
remaining 653 kg.
A minimum weight is enforced for reasons of
safety – to ensure the teams don’t skimp
on their cars strength in pursuit of speed.
Every kg of mass you have requires more energy
to accelerated around a track, as you’d
know if you ever had to run while carrying
massive bags.
By the way, mass and weight do mean different
things but I’ll be using them fairly interchangeably
throughout this video as it doesn’t really
matter in this context. If you want to know
the specific differences I’ll explain over
the credits.
OK, so now we have to weigh the driver and
seat separately to the rest of the car. In
what way is this different to weighing the

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car and driver as one mass? A smaller 65 kg
driver and a larger 75 kg driver will weight
identically when combined with their cars,
so why is it so much easier to have a smaller
driver in your car that drivers have been
known to lose unhealthy amounts of weight
to benefit performance?
The answer is weight distribution.
See cars are built as underweight as possible
and then brought up to the minimum weight
via ballast. Ballast is the term given to
heavy material strategically placed around
the car for stability. Ships and aeroplanes
also use ballast.
Often heavy metals like tungsten are used
to this purpose. As they are so dense, very
heavy masses can be placed precisely without
taking up room.
So how does weight distribution affect an
F1 car?
Well, there are a number of factors at play
here. One is how much you want to load up
the tyres.
See the tyres are the only points of the car
that touch the ground so ultimately all the
weight of the car is borne by the tyres.
If you force a tyre to bear too much weight
it can start to overheat more quickly as it’s
used, which can lead to degradation and loss
of grip.
If a tyre has too little weight pushing it
into the ground then it is more prone to slip

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and can more easily lock under braking.
Pirelli of course design front and rear tyres
with certain expected weight demand thresholds
and in fact the rules mandate that during
qualifying (when the car is low fuelled) the
“weight applied on the front and rear wheels
must not be less than 333kg and 393kg respectively
during qualifying.”).
Secondly, we have to consider acceleration
All the acceleration comes from the rear wheels,
as these are the driving wheels. More weight
over the rear axle (to a point) leads to better
traction through and out of corners, meaning
better acceleration. Under balance the rear
of the car and traction will suffer.
What else happens when we move ballast around
between the front and rear of the car?
Well now we need to have a little understanding
of two things: moments and inertia.
A moment is a turning force.
Specifically, when we think about moments,
we think of a pivot point and applying a force
a certain distance from that point.
Imagine a door. It shouldn’t be hard, there’s
probably one right behind you. If you apply
a force – i.e. push – against the door

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close to the hinge it’s much harder to get
the door to turn than if you apply the same
force far from the hinge.
Just FYI: the actual definition of a moment
is the force you apply multiplied by the distance
from the pivot that you apply it.
So on a see saw, you can place a 1 kg weight
2 metres from the pivot and a 2 kg weight
1 m from the pivot and it would all balance
out.
So, with that in mind, think what would happen
if we put a 100 kg weight right at the end
of the see-saw, let’s say it’s 3 metres
out. It would be really hard to get the see-saw
moving, right? But if we moved the mass more
towards the centre, suddenly it becomes a
whole lot easier, doesn’t it?
And that’s the first lesson – it’s hard
to turn something whose weight is far from
the pivot point.
You can try this – carefully. Hold a hammer
from the end of the stick part and start to
swing it – carefully. It’s much harder
work that holding it from the hammer end,
because this time all the weight is much closer
to the turning point.
So back to the F1 car: because of its layout,
you’re turning it around a point between
all the wheels.
You don’t want the centre of mass to be

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too far from the centre of the car or it will
require more energy to get the car turning
quickly and it won’t be particularly nimble.
Now let’s consider inertia
But quickly first, let’s define the ‘centre
of mass’, which you’ll often hear as the
‘centre of weight’ though that’s less
accurate.
It’s very simple – the centre of mass
is the average point of all the mass in an
object. A pretty regular, homogenous cuboid
of plastic would have a centre of mass bang
in the middle. But if that block was half
plastic, half lead, then the centre of mass
would be way more towards the lead end of
the block as the lead part has more mass.
Therefore, on average, the mass of the block
would be much more towards the lead end, and
that’s what the centre of mass represents.
It’s also the balance point of the object.
If you placed that plastic/lead block on its
centre of mass, if would balance perfectly.
With our F1 car, if we start moving the centre
of mass around by re-positioning our ballast,
we’ll see the weight load on each tyre change
accordingly.
Inertia then.
Inertia is the resistance of an object to

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change in velocity.
If a car is travelling along, it actually
doesn’t want to be moved around. It’s
going to keep going as it is until you put
some force in to make it do something else,
like braking or steering or accelerating or
crashing into a barrier.
The more mass something has, the more resistant
it is to change.
A double decker bus driving at 60 miles an
hour is harder to stop than a Mini Cooper
at the same speed.
So, bearing inertia in mind – that bodies
of mass will tend to keep on going and resist
being yanked about – let’s take a look
at a car cornering with all its weight at
the rear.
The car is going straight and then turns right.
But all the weight wants to keep going straight.
As the front steers in, the back really wants
to keep going and this leads to the back sliding
out, which we’d call oversteer.
On the flip side, if we bunged all the weight
at the front, all the weight at the front
would want to carry on. The front is resistant
to being turned in and struggles to get the
car steering as much as we like. This is called
understeer.

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Finally, we’ve looked at front-to-read distribution
but let’s thinking about top-to-bottom weight
distribution
See, ballast tends to be placed as low as
possible to lower the overall centre of mass.
But why is this useful.
Well let’s consider inertia again – particularly
if the centre of mass is quite high up.
The car will turn in, but all this mass will
resist. So the top of the car will be the
most sluggish to respond and lean out as the
bottom of the car moves out from under it.
This is car roll, when the car rotates along
the centre line.
The problem with a car rolling too much is
it starts to unbalance the tyre loads. The
inside tyres start to lift and the outside
tyres take all the weight.
Body roll is heavily controlled by suspension
engineering – but that’s definitely for
another video.
Bringing the overall weight as low to the
ground as possible is a great help at reducing
body roll and keeping the car balanced through
the corners.
Which brings us back to the driver.
See a taller, heavier driver will naturally
be carrying their weight quite high up compared

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to a lighter driver with the extra low, low
ballast.
Enforcing the driver/seat weight to meet a
strict minimum means a lighter driver loses
a lot of the advantage of having a lot more
ballast to be strategic with.
The obvious, fairest place to put the mandated
seat ballast (to bring the weight to 80 kg)
is not down on the floor but halfway up the
seat, roughly where the actual driver’s
centre of mass is. I’d hope the FIA mandate
and minimum height for seat ballast.
I hope this helps you understand why the new
rules are finally separating the minimum weights
of the driver and car. Any questions – leave
them in the comments.
Thank you to my patreon patrons for supporting
me with these videos.
And now – what’s the difference between
weight and mass? Well mass is the amount of
“stuff” in an object. I.e. a human adult
is made of, say, 70 kg of stuff. Weight is
the measure of how much that stuff pushes
down towards the ground. Now, for a the most
part in every day life, these things are pretty
similar. A 70 kg person pushes down with the

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weight that 70 kg of anything would, right?
Except if they’re going up in a lift in
which case they push down harder. Down in
a lift? They push down less. On the moon?
They weigh less. In space, they weigh basically
nothing. But their mass stays the same. See,
once you start doing things with a mass, the
weight can change quite a lot, which is why
they are technically different things but
you don’t have to think about that when
following a recipe. Unless you’re a chef
on the moon.
