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Never Do a Superhero Landing

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13:57   |   May 31, 2018

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Never Do a Superhero Landing
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  • - 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.
  • 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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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