- Here's why you should
never land like a superhero.
Superheroes love to make an entrance.
And if they are flying or falling,
that entrance is frequently
them crashing down,
knee and fist first, in a stance
that is undeniably cool,
especially in slow motion.
But unless you are a
you should never break
out a landing like this,
because it's almost perfectly designed,
from a scientific
standpoint, to break you.
The superhero, or three-point, landing
is where you land in a half-crouch,
with one knee and sometimes a fist or two
impacting the ground directly.
It surely looks cinematic, but as I claim,
like Deadpool claims, it is really, really
hard on your knees, and
it is totally impractical.
But why would the superhero landing
be impractical or dangerous?
How is it any different
from landing on your feet?
What is going to make any
landing that you attempt
harder or softer is gonna come down
to impact force, and if you
are falling on this planet,
that force is gonna be applied to you
by the surface of the Earth, or whatever
comes in between you and the surface
of the Earth when you are falling.
Physics nerds like me like to say that
it's not the fall that kills you.
It's the M delta V over delta T.
Does not have the same ring to it.
But this equation describes how quickly
something's momentum changes.
Momentum is mass times velocity.
So right before impact, the
more something's momentum
is about to change, go from some velocity
to zero, or the more
quickly all that momentum
comes to a complete or partial stop,
the more force it is going to take.
That is why something like an ant
with a tiny, tiny mass
and therefore momentum,
can hit the ground after
falling off of a cliff
and be fine, but Deadpool cannot.
Ah, ah, ah, it's on my hand!
You cannot change you
mass, and you can't change
Earth's gravity, so the
easiest thing for you to do
to reduce the forces on you when landing
is to extend the amount of time it takes
for your momentum to
come to a complete stop.
And to demonstrate this,
consider this simple egg.
It's a wonderful little
that is famous for both its
strength and its fragility.
Now, if I threw this egg up
and let it hit the hard ground
that I'm standing on, it would break.
But if I extend the amount of time the egg
comes to a stop in by catching it
with something soft, like this sheet...
Heh, the egg is fine, as you can see.
Timing is incredibly
important in this calculus.
When the timing is extended,
then the egg is fine.
But if the time is shortened, then...
Ow, they get it!
Oh, it hurts.
Oh, is it dripping?
How much is it dripping?
Did you get it?
How does all this apply
to the superhero landing?
Well, let me show you
by getting out of here.
Comin' in hot!
Here I am at my local rock-climbing gym.
Because time to stop is so
important for impact force,
let's time how long it takes
me to attempt a normal landing
and a superhero landing respectively.
My SHL attempts averaged
about a third of a second.
And here are my normal landing attempts.
These averaged a little
over half a second.
As you can see, the SHL stopped
me quite a bit more quickly,
and trust me, you can feel
that force difference.
For superheroes that
fall from great heights
and therefore land at great velocities,
this time difference
is even more important.
So now let's estimate the kinds of forces
that a real superhero like Iron Man
would undergo during a superhero landing.
How about when Iron Man slams down
on that stage during Iron Man II?
I know, I know.
But I like Sam Rockwell.
For the sake of simplicity,
I'm gonna assume
that Iron Man first stabilizes himself
and then turns off his repulsors
to freefall from a distance
of 30 meters above the stage.
About 100 feet.
And I'm gonna assume no air resistance,
because it is easier that way.
Now, knowing the fall
distance and the acceleration
due to gravity, we can use
these kinematic equations,
or equations of motion, to first find
how long it takes Tony
to freefall to the ground
during the superhero landing, and then
his velocity right before impact.
Plug all of that into
along with Tony Stark's mass,
his final velocity from
this kinematic equation,
and the time it takes
for Tony Stark to come
to a stop, which looks
like just a single frame
of the movie in Iron Man II, and you get
a total force when Tony Stark comes
slamming down onto that stage
of 112,000 newtons,
the equivalent of a head-on car
collision at highway speeds.
No, Mr. Stark, wait!
I don't feel good!
Treat me like a Spiderboy!
Speaking of car crashes,
how about another example?
Like when Batman crashes
down on the hood of a van
during a superhero landing
in The Dark Knight.
Using the same equations but
changing some values around,
I'm assuming that Batman
weighs 95 kilograms,
that he's falling from a
distance of around six meters,
about two stories, and he comes to a stop
within four movie frames, and
you find that in that scene,
when Bruce's knee comes smashing down
on the top of that van, he is enduring
over 6,000 newtons.
Now, for context,
estimates for what it takes
to shatter the strongest
bone in your body,
the femur, come in at 4,000 newtons.
That means that without some supersuit
or something else to protect you,
these kinds of superhero landings,
at least in these examples,
would totally break you.
I do not want to be here when
that starts to grow back.
The only thing that you can really control
in these force equations
is the stoppage time.
And that's exactly why,
during a normal landing,
we bend our legs.
It extends the amount
of time our momentum has
to come to a complete stop, and thereby
it lowers the forces on our bodies.
And trust me, you wanna do that.
You feel the difference.
But do not take my word for it.
For the sake of completeness, and to prove
just how much of a difference
a simple difference in timing can make,
I ramped it up.
Okay, so here I am about
to attempt a normal landing
from the exact same
height that Batman landed
in The Dark Knight, the scene
that we just went through.
There's a lot of padding under me,
and our positions aren't exact, but it's
close enough for our purposes,
and I didn't want to hurt myself.
Clocking my stoppage time here,
it takes me just about 0.275 seconds
to come to a complete stop.
If you extend Batman's stopping time
in that Dark Knight
scene to my stopping time
doing a normal landing
from the same height,
you get a reduction in force
of a full
Now, I know that Batman
was trying to crush
that bad guy's van, but
what I am trying to prove
is that the difference
between a normal landing
and a superhero landing,
even though the times
are just fractions of a second,
can be the difference
between maybe walking away
from a landing and definitely not.
Because this percentage reduction
takes the force that's on Bruce Wayne
well out of the
femur-shattering bone zone.
Because there is little to no leg bending,
the superhero landing is almost designed
to break you, but if you
could withstand these forces,
it would make for a pretty good entrance.
That is annoying.
Looking back at those
SHL forces we calculated,
those forces are gonna be
acting over some surface area.
Let's just assume that's
mostly the surface area
of a knee.
Now, I measured the
surface area of my knee,
and it came to around
39 square centimeters.
Now, if Tony Stark came flying in
and did a superhero landing with the mass
and velocity that we assumed earlier,
then the pressure at his knee upon impact
would be nearly 30 million pascals.
The compressive strength of concrete
ranges from around 17 to 28 megapascals.
Which means that if a hero like Stark
came screaming in for a superhero landing
with forces at his knee
like we are assuming,
then just like in the
movies, at point of impact,
the concrete would
crack, and it would crack
other similarly strong
materials, at least if
those heroes had the same mass
and velocity of Mr. Stark.
Wait, don't go!
I still don't feel goo...
But even though the required
pressures are there,
to make a superhero
landing really look right,
you would need another particular power.
Smartboy Isaac Newton
came up with a very clever
approximation for how far
one object would penetrate
into another if everything was moving
at sufficiently high velocity.
He found that the depth of penetration
will depend on the length of the object
and the ratio of the densities
of the impactor and the impacted.
For example, a bullet
versus Jell-o will have
a very high ratio, meaning
the penetration will be high.
But for something like wood
versus the density of steel,
the penetration is very low,
because the ratio is low.
Now, this approximation
really only applies
to really fast-moving objects like bullets
and meteors, but it gets
us where we wanna go.
A normal human knee, made
out of skin and bone,
is much less dense than concrete,
which means that without some power
like superhuman density, a human knee
during a superhero landing
is more likely to smoosh
Some superheroes might still be able
to pull off this grand entrance, though.
Remember in the first Iron Man film,
when Tony Stark says that his suit
is made out of a gold titanium alloy?
Well, gold is the seventh-most
dense element on Earth.
It's even denser than uranium,
and uranium is highly valued in weaponry
for its penetrating power
because of its density.
So if Iron Man had an ultra-dense suit,
or if another superhero had an ultra-dense
property to their body because
of some other superpower,
then there's actually a good chance
that they could come in
for a ground-shattering
superhero landing without
Come on, man!
I'm already like Bucky.
But you, with your squishy human body,
should never land like a superhero.
If you're falling from a
height of a meter, it's fine.
Trust me, I tried.
But any higher than that,
and the three-point landing
is impractical on almost every level.
Deadpool was right.
Even if you could
withstand the high forces
that the superhero landing imposes on you
by minimizing the amount of time
your momentum has to come to a stop,
you still need another
superpower like superdensity
to make sure that you do not
smoosh during the process.
The three-point landing is
already a term in aviation.
It describes when an airplane
lands with all three wheels
at once, instead of two and then the nose.
It's considered bad, because
the nose landing gear
isn't designed to take
those kinds of forces.
And neither are your knees.
I know it doesn't look as cool,
but your patellas will pa-thank you.
Time to jump on outta here.
Oh, my quads.
Can't do it.
It was for science.
I mean yes, if you're falling 100 feet,
you're gonna get messed up regardless.
But what I'm saying is that you will be
messed up less if you land normally,
because it extends the amount of time.
That's the same thing
that parkour guys do.
They land and roll, and
they're falling further
than they otherwise
would, and that increases
the amount of time and lowers the force.
That's how they can
drop from so far and...
I am limping around,
around the void today.
My quads are killing me because of this.
Morpheus knew that.
That's why he always landed and tried
to hurt someone with his knee powers.
Thank you so much for watching, Robert.
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Grab your new Because Science merch here: https://shop.nerdist.com/collections/because-science We've seen a lot of heroes from Batman to Iron Man do superhero landings, but are they actually a good idea? Kyle does some number and bone crunching on this week's Because Science!
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Artist: Andrew Bowser
Learn more: • THREE-POINT LANDING: http://bit.ly/2kC25mD • FREE-FALL KINEMATICS: http://bit.ly/2kC2a9V • COMPRESSIVE STRENGTH CONCRETE: http://bit.ly/2skzYN7 • IMPACT DEPTH: http://bit.ly/2FDBH5t • FULL CALCULATION: http://bit.ly/2IXUAFh • DENSITY OF CONCRETE: http://bit.ly/2J5OnDe • DENSITY OF BONES: http://bit.ly/2J1Bx8M