- 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 superpowered individual,
you should never break out a landing like this,
because it's almost perfectly designed,
from a scientific standpoint, to break you.
Ow.
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.
Ew.
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 evolutionary creation
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!
Ooh.
Oh.
Oh, it hurts.
Oh, is it dripping?
How much is it dripping?
Ow.
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.
Wow.
So cinematic.
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.
Mr. Stark!
It's me!
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 our it's-not-the-fall-
that-kills-you equation 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!
Comfort me!
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.
Whoa.
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
39%.
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.
It's better.
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.
Right, Batman?
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...
Oh boy.
But even though the required pressures are there,
to make a superhero landing really look right,
you would need another particular power.
Superdensity.
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
than smash.
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 smooshing themselves.
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.
Because science.
Time to jump on outta here.
Oh, oh.
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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