- It says kilonewtons...

And after this video,

you will have a much better understanding

than probably 99% of the
rest of the climbers,

what these kilonewtons actually mean,

and what forces are involved
in real climbing falls.

And then I will explain
why big, big whippers

are often much softer than small falls.

But first, let's find out what is force.

I like to play with my
Instagram followers,

so I decided to ask them
what comes to their mind

when they hear the word force.

Half of the people said

that it has something
to do with "Star Wars".

Fair enough.

And then before you start thinking

that half of my Instagram
followers are really smart,

I have to say that majority
of them didn't vote it at all.

So I imagine something like...

What is force?

(lively music)
(electronic buzzing)

Okay, but those who wanted to sound smart

said that force is mass
times acceleration,

which is the formula
that Newton, this guy,

came up with.

- [Newton] Ooh yah.

And that's why we
measure force in Newtons.

Which to me is a little bit
funny when you think about it,

imagine Newton.

(gentle music)

So we measure mass in kilograms,

and we measure acceleration
in meters per second squared.

Then we should measure force in Newtons.

(clapping)

So to put this formula into perspective,

it's like one Newton, this guy,

is pushing one kilogram of mass

and that makes that mass to accelerate

by one meter per second, every second.

So here I have a carabiner.

If I put all my weight on it, like so,

the question is, what's
the force right now

into this carabiner?

So if we look back to the formula,

we can say that mass is my mass

multiplied by acceleration.

What acceleration?
I'm hanging on a tree.

There is no movement,
no acceleration...

or is there an acceleration?

(upbeat music)

Look, so you've probably
seen this experiment before,

I have heavy object and a light object.

And the question is, if I let go

both of them at the same time,

which one is gonna hit the ground first?

Let's try.

So yes, they fell at the same time,

because that's what gravity does,

it makes objects fall at
exactly the same acceleration

of 9.8 meters per second per second.

So then I'm hanging on this carabiner,

gravity is pulling me down.

But in order for me to not move down,

there must be opposite force,
which would be pulling me up.

Here I have a spring.

While the gravity is
pulling the rock down,

the spring is pulling the rock up.

So the carabiner is actually
like a very, very stiff spring,

which is pulling me up.

The molecules of the carabiner
when I'm hanging on it

are being spread apart,

but they like to stay
together, so they pull back.

You can't see this
expansion of the *carabiner

on low forces, but you can on big ones.

And so it turns out that this carabiner

has to accelerate my weight up

at the same 9.8 meters per second squared,

which turns out to be about 600 Newtons.

Yep, 600 of these need to
hold one skinny guy like me.

Okay, moving on, this carabiner says

that it can hold up to 26 kilonewtons.

Kilonewton is basically
a thousand Newtons.

So it means that it
could hold about 40 me.

I wish I would have a clone machine,

so I could demonstrate this to you.

Then imagine how many videos
all of these me could create.

(bright music)

So if you wanna see us
create more videos like this,

click the join button, it really helps.

And I promise I will
spend every single penny

I get from you guys on
buying a clone machine.

Enjoy.

(chuckling) Okay, so you can hang 40 me

on one single carabiner,
that's pretty impressive.

Although there are things
that you must know.

First of all, all of these ratings

are for new equipment,

wear and tear does not
go into that rating.

How bad is that?

Well, I asked my friend,
Ryan from YouTube channel,

HowNOTtoHighline because he has a hobby

of breaking stuff.

And according to his tests,

most of the metals tend
to last pretty well.

Although with soft things,
things are totally different.

- [Ryan] Black Diamond sling
with a 22 kilonewton MBS.

(machine whirs)

(metallic clang)

What? Was the MBS
on 22 kilonewtons?

- [Man] Yeah.

- Yep, a sling rated at 22
kilonewtons broke at six.

And here is another one.

- [Ryan] Woo, that's a great condition.

- [Man] Would not whip.

- [Ryan] No, not whip.

I would tie my dog to this though.

(machine whirs)

All right.

- [Man] I wouldn't tie
a very big dog with that.

- [Ryan] (giggling) All right,
let's see how big of a dog

could you have tied with this?

Ooh, a Chihuahua.

(man chuckles)

- Yeah, so if you're one of these people

who like to save money and use very old,

worn down slings, good luck.

- [Ryan] 24 kilonewtons,

(machine whirs)

that did not stretch that much.

Oh, guess, guess.

- [Man] I saw.

- [Ryan] Four kilonewtons,
what the fuck, man?

- 4,000 Newtons, okay how
much does such sling can hold?

Well, that's pretty easy.

Just divide 4,000 Newtons by 9.8.

Or if you want easier, by 10
and you get 400 kilograms.

That sounds quite a lot. 
No? 400 kilograms?

Well, all of these conversions
from force to kilograms

that I have been talking so far

are based on the fact that the
weight is hanging statically.

Once the thing starts
falling, everything changes.

- [Man] Go.

(metallic clanking)

- So what you have just
seen is a clip from DMM,

where they dropped 80 kilograms of mass,

and that broke a brand new Dyneema sling.

Now my goal is not to scare
you, it's the opposite.

I want to bring the
awareness that climbing gear

is not magic, and if you use
it incorrectly, it might fail.

Fun fact, do you know
this joke that climbers

like to say when they
fail on their climbs?

That today is a high gravity day.

Well, turns out that's true,

gravity does change from month to month.

So if you are one of those people

who like to complain that
today is a bad humidity,

or bad temperature, now you
have a right to complain

that today's a bad gravity day, yay!

Okay, let's see what happens

when objects like us,
climbers, start falling.

That was a 10 meters fall.

Let's see how much force such fall

would generate to the climber.

The formula for that would be similar

to what we had before, except
that we need to multiply

this by the distance
the climber was falling,

and divide by the distance
the climber was slowing down.

And did you actually notice

how soft the fall for the climber was?

So imagine driving a car in a highway,

and pressing on the brake
gently while you come to a stop.

No problems right?

Now imagine you are not driving so fast,

you're in a city, you're driving slowly,

but you slam on the brake,

that would not feel very nice, right?

So here is the first thing
I want you to remember

out of this video, the
impact to the climber

will always be multiplied by the distance

the climber was falling,
divided by the distance

of the slow down phase.

So let's calculate, their falling distance

was about four quickdraws,

and their slowdown distance was about

two and a half quickdraws.

And we get about 860 Newtons.

Or if we would replace her with a standard

80 kilogram climber, that
would be about 1.3 kilonewtons,

which is not much.

Although this formula 
has a little problem

because it will always give you
the value of it just slightly lower

than it would be in real life.

But showing you how to
calculate more precisely

would mean that most of you would probably

just leave this video right here.

But we don't need to do that,

because we can rely on real
life experimental data.

And who is the boss at
providing such data for us?

- Hi, I'm Ryan Jenks and-

- And then that's enough
advertisement for you.

What they did in this video,

they put a device measuring
the force on the climber,

and made a series of falls.

- (laughing) Zach.

For science, woo hoo.

That puts me at 1.87.

- So most of the falls,
that in my opinion,

would be a good belaying example,

were below two kilonewtons.

Now let's take a look at
these two extreme examples.

Climber on the left is
five meters above the bolt,

so that would be 10 meters fall

plus the slack in the system.

The belayer probably has
about one meter of slack.

And then there is probably
one more meter of slack

in between the quickdraws.

So in total, we are
looking at 12 meters fall.

While climber on the right is
only one meter above the bolt.

And let's say that
belayer is really afraid,

and he's going to give a very
hard catch for the climber.

So we are looking at two meters fall.

So a massive 12 meters fall,
or a small two meters fall.

Which one do you think
is going to be softer for the climber?

Well, let's see, we know how much

the climbers will fall.
But now we need to find out

the slowed down distances
for both of the cases.

And that depends mainly on two things.

First is the displacement of the belayer.

On a big, big whipper, the
belayer will probably fly

about two meters, while on a small fall,

let's assume very common
mistake for beginners,

where the belayer just takes the slack out

and belays very hard.

And the second factor is
the stretch of the rope.

Rope manufacturers claim
that if you put 80 kilogram

mass on a dynamic rope statically,

like so, without movement,
the rope will stretch 10%.

And dynamic stretch, when
you take a lead fall,

is up to 30%.

Well up to 30% is not very helpful for us.

What we need to know is
the stretch of this rope

from two to four kilonewtons force,

that's where the lead falls are.

And yet again, I was texting Ryan.

- So, I'm gonna pull some dynamic rope,

to see how much it stretches.

At first, we thought
it's gonna be very easy,

just go to the park, stretch
the rope to different forces,

and measure the elongation of the rope.

Well, sometimes easy is hard.

When you stretch the rope to certain force

and leave it there, the force will start

dropping on the rope, the
rope kind of just gives up.

While this is very interesting,
it's not critical for us.

The only thing he needed
to do is to pull the rope

as fast as he can to desired force,

and measure the stretch.

- [Ryan] Okay, oh my God,
that's the seven mark...

6.9 meters... it stretches...
when you pull it...

a dynamic rope... to four kilonewtons.

But then there is
another interesting factor,

once you load the rope to high forces,

it takes some time for the rope

to get back to its original length.

This is what's known as rope resting,

and it was really cool
to see this in action.

- [Ryan] See the Grigri
getting pulled back slowly?

Super interesting, probably
way more interesting

to me than it is to you right now.

So after he spent like
four hours in the park

pulling the ropes, the
results were that on forces

from two to four kilonewtons,

the rope stretched to about 20%.

Great, so let's use that
in our calculations.

On a big fall, we have 27
meters of rope in total,

so that would be 5.4 meters of stretch.

While in a small fall, we
have five meters of rope,

and that would be one meter of stretch.

However, our belayer is
panicking and taking hard,

so he will take half of
that stretch for himself,

leaving only half a meter
of stretch for the climber.

And ta-da, the big, big whipper

will be two and a half
times softer for the climber

than the small fall.

Oh, I love fun facts,

here is another one.

Imagine that you were climbing and failed,

but humidity was good,
temperature was good,

even the gravity was good that day.

You can still blame the moon.

- [Narrator] Negligibly but truly,

you weigh about a million
of your weight less

when the moon is directly above you.

- So if you wanna ascend,
climb when the moon

is directly above you, you're welcome.

I remember I was projecting
this really long route

of 35 meters, and the first
time I managed to link

all the cruxes and arrive at the anchor,

the moment when I was pulling the rope up

to clip the anchor,

my belayer couldn't see me very well,

so he just gave me a lot of slack.

And on top of that, the
bolt before the anchor

was really far, really ran out.

So while I was dragging the rope up,

I lost my balance and took a fall.

The wall is flying in front of me,

and I'm thinking, "Why I'm still falling?

Hmm, this is unusual."

Then I stopped and looked up,

it was maybe five or
six Quickdraws above me,

probably about 15 meters of fall.

But the fall was super soft,
it's like riding an elevator.

So here is another
takeaway out of this video,

if the climber is really high up,

he has a lot of rope to absorb the fall.

So as long as he doesn't
fall onto something,

the fall will be soft, no
matter how you belay that.

However, if the climber is not so high,

he doesn't have so much
rope to absorb the fall,

The soft dynamic delaying
is really important,

and you can ask any light climber,

how many times they
had their ankles broken

due to hard catches.

Okay, let's switch gears a little bit.

Let's talk about friction,

'cause the more friction you have,

the harder the fall for
the climber will be.

And here is a very
extreme example of that.

- As you can see right
here, we Z dragged it.

And so we're gonna have a
lot of friction when I fall.

And whoo, for science.

Do it!

Oh my God!

- So when you have a lot of friction,

the rope close to the
climber stretches normally,

but the rope closer to belayer
doesn't stretch that much.

It's like having shorter
rope and heavier belayer

at the same time.

And although the force to the harness

was only two and a half kilonewtons,

a lot of the force went
pendulum into the wall.

- Do it.

- And that's how we break ankles.

So extending the Quickdraws
not only helps you to clip

and avoid situations like this,

(upbeat music)

(climber straining)

But also reduces the impact
forces for the climbers.

Okay, let's circle back to the DMM test,

breaking the sling.

Dyneema slings are very static,
they don't stretch at all.

And I hope that by now you understand

that this sudden stop
can create huge forces.

If not, ask somebody to slap you.

This stop on the face will be basically

what you need to understand.

So let's make a very wild

and probably very inaccurate guess

that this sling would stretch
to about five centimeters.

So if we drop 80 kilograms of mass,

the distance of 120 centimeters,

and the absorption distance
is only five centimeters,

we are looking at 19 kilonewtons.

If that is not gonna break the sling,

it's definitely gonna break you.

Woo, if you're still watching,

that probably means that you should be

at least a little bit geeky.

So here is a dessert for you.

There is no gravity.

Yeah, objects don't attract each other,

there is only space time.

- You feel as though you're
being pushed into the ground,

not because of a force called gravity,

but because time is moving faster

for your head than for your feet.

- This and all the other
resources that I use

to create this video will
be in the description.

And now please go send some love to Ryan

for providing me with all
of his experimental data

that I used in this video.

So don't forget to subscribe
and support our channels

if you wanna see more content like this.

Enjoy.