# Physicist Breaks Down Superhero Physics From Movies & TV | WIRED

published on July 2, 2020

hi my name is Rhett Elaine Brett is a

physics professor at Southeastern

Louisiana University today I'll be

breaking down amazing feats of physics

from superheroes in movies and

landing that's really hard on your knees

you know one of the great things about

Deadpool both in the comics and in the

movies is that he breaks the fourth wall

and interacts with the audience I know

right in this case he talks about the

superhero landing superhero landing

superhero wait for it the idea is a

superhero lands with one knee one fist

and a foot on the ground so three

contact points but it's a very sudden

move it's not like a normal landing it

does look really cool and I think

happens all the time

[Music]

and is that better than the way a normal

person would hit the ground the answer

is no that's really hard on your knees

totally impractical they all do so you

got to think about the forces acting on

a person while they're landing from

falling from somewhere the key is to

have the force as small as possible one

way to do that is to increase the

distance over which you stop so if I

jump and land on the ground I let my

knees Bend and my center of mass moves

down while my knees Bend increase the

distance over which I stop and decreases

the force there's a thing called a

parachute landing fall and you don't

even stand up you hit you bend down you

roll over on the ground and you increase

the distance over which you stop even

more that's the best way to do it the

superhero landing it's just gonna be a

bad idea we all know how this turns out

kinetic energy black panther

kinetic energy is a quantity you can use

to describe objects in motion we have

momentum which is mass times velocity

and then there's kinetic energy which is

one-half mass velocity squared

you know kinetic energy isn't a real

thing it's a way to view nature it's a

way to view interactions so anything

that's moving would have kinetic energy

if I take a baseball and I throw it it's

moving it has mass so it has kinetic

energy black panther suit

somehow has an interaction between the

bullet and his suit to take the kinetic

energy of the bullets and store it in

some type of internal battery and then

once he has enough energy stored up he

can release it in a energy pull of some

type to do whatever he wants I'm not

sure exactly how it works that's what

makes him Black Panther and the

technology of Wakanda is beyond me to

fully understand recoil wonder why

[Music]

so what is recoil suppose I am standing

on a frozen lake and I have a basketball

or some heavy weighted ball and I throw

the ball well the ball's momentum is

gonna change because I exert a force on

it but the ball pushes back on me with

the same force so I'm gonna have the

exact same change momentum that's gonna

make me move back course it makes

complete sense this is the idea of

recoil when you throw something one way

you go back the other way so a bullet

has momentum it's moving it has mass it

has but it turns out that it's moving

really fast but it has pretty low mass

and it doesn't have that much momentum

if you collide a bullet with a bracelet

or a person in some way then that person

would have to recoil with the same

momentum but the person has such a large

mass the recoil velocity would be super

tiny and so you don't really get recoil

from normal bullets when they hit people

so in this case Wonder Woman deflecting

a bullet it should be fine is there

anything else you wanna show me contact

area Justice League I'll take the ones

on the right

the Superman building things impossible

super-strength even with that he

couldn't do this so imagine you had a

jello cake it's like a big blob of

jell-o this big is this a bad time to

bring up my blood sugar and you wouldn't

lift up the jello with a toothpick by

pushing on the bottom the toothpick

would just go right through the jello on

top of that the jello would probably

break in half too so both of those

things are a problem Superman's pushing

in the middle of the building trying to

support the whole thing he would just

poke right through the whole thing and

the building would fall if he wants to

actually lift the building he needs to

increase the contact area either get

bigger hands which that's probably not

gonna happen or he could possibly have

some cables that attach to multiple

locations on the building and then lift

it from the top maybe it doesn't look as

cool but it'd be more plausible at least

weird and so many ways strength

spider-man homecoming

at the beginning spider-man uses his

webs to connect one side of the boat to

the other in an attempt to prevent it

from falling apart and it doesn't work

[Applause]

it could be any number of reasons

particularly he just doesn't have enough

webs to actually exert enough force

between the two halves to prevent them

from falling apart the ultimate tensile

strength the point at which the tension

breaks were the string breaks for

spider-man's webs I mean you'd first

need to know what's made of and then you

need to know the diameter of it it's

really difficult to estimate how much

that could be a better way to approach

this would be to calculate the tension

that he exerts on the boat when it

breaks the the more they lean the

greater the gravitational force is on

that piece to pull it apart and you need

a lot of force to keep these two things

together and maybe his webs just aren't

strong enough to do that

great job Peter

I suspect the 98% means that the total

force needed to keep one side of the

boat up is 98 percent of what you need

to prevent it from falling over if the

force isn't great enough the boat tilts

and it stretches that web and eventually

the web breaks and then you have no

force from the web and that makes more

webs break and have a sort of cascading

failure hi spider-man band practice

[Applause]

the Ironman suit may be more successful

at pushing the boat back together for a

couple of reasons number one it's

possible that his mini micro thruster

rockets that attach to the side of the

ship are just stronger than spider-man

twelves the second big thing is that

those forces can keep moving as the boat

moves

whereas spider-man's force is a static

force once you stretch a pass out it

can't it can't pull it back together it

just prevents it from falling apart

further the ship floats because it

prevents water from getting inside and

makes it overall effective didn't see

less than water once you violate the

integrity of the hull game's over that

thing's is gonna sink really fast

I don't think spider-man's gonna have

enough time to push it back together I

don't think Ironman is gonna have enough

time to push it back together now it's

just a movie so we're okay with that

what do you want me to do I think you've

done enough

terminal velocity Captain America the

Winter Soldier

see where to parachute

no he was

[Music]

so when Captain America jumps out of the

plane there's really two forces that

come into play the first is the

gravitational force that pulls him down

but there's another force as he starts

to fall an increase in speed there's an

air resistance force he's colliding with

the air molecules and those air

molecules push back on him in the

opposite direction that he's moving and

in fact it gets to the part where it is

the same as the gravitational force now

he has an upward pushing force in a

downward pushing force that are equal

magnitude with equal magnitude forces he

moves at a constant speed we call this

terminal velocity because he doesn't get

any faster when Captain America first

leaves the plane he starts off in a

standard skydiving position this

position allows the largest surface area

for the highest air resistant force and

therefore the lowest terminal velocity

it also allows you to move your hands in

a way that you could actually control

your motion by pushing the air in

different directions towards the end of

the jump he actually goes into a more

vertical position this decreases the

surface area that collides with the air

and makes him fall even faster he wants

to hit the water feet first so he flips

over hits the water feet first in like a

pencil dive or pencil jump and the nice

thing about the feet first vertical

position when hitting the water is that

it will make him penetrate the deepest

into the water which increases the

distance of where tree stops and

decreases the stopping force and gives

them a better chance of surviving I mean

it's Captain America so these programs

survive no matter what net force Iron

Man 3

see that guy I'm gonna swing by are you

just gonna grab I'll Electrify your arm

you won't be able to open your hand we

can do this Heather

once you start having multiple people in

a chain hanging together the person on

the bottom they're just hanging like a

normal person

the next person has to pull with the

force equal to their own weight and the

force of the person pulling down below

them which is their weight the third

person has to pull with the force of

three people and you can see it starts

getting really large and uncontrollable

Ironman wants to solve this problem by

essentially electrically shocking their

muscles into contracting so they can't

let go

I'll Electrify your arm you won't be

able to open your hand I don't think

that would work for a number of reasons

I get a lot of this it's okay first if

you get like five people in a line it's

probably not just about muscles things

start to break in human arms and it

wouldn't work the second thing is that

you can have an electrical shock make

people's muscles contract but the

problem is that you normally need a

closed circuit you need a path for the

current to go there and all the way back

and he just has a chain there's no way

for the current to get back to Iron Man

and use of power supply to force this

shock gripping nice work guys

good team effort all around go us miss

integration the boys when you ever so a

trains running really quick and he runs

into the girl what would really happen I

mean it's such a hard question because

it really depends on a train it is he

invincible or is he like just a really

fast normal human if he's a really fast

normal human colliding with a stationary

human they would both have the same

amount of damage because if he pushes on

her with the forest she pushes back with

the same force so whatever happened to

her would happen to him in the clip she

just turns into goo so clearly he has

some other powers other than just being

super fast would he just push right

through or would which she recoil well

it really depends on again how fast he's

going and how he actually hits her one

part of him hits her before the rest of

him does he could essentially poke

through her I know that's kind of gross

and once he's done that he he kind of

disables the integrity of her body such

that it's possible she could go splatter

it all over the place

Oh watching that clip there is one issue

that that is weird if he's running this

way and hits her why does some of the

blood go back on on her boyfriend if it

appears that he hitting her would push

all the blood in the same direction he

was moving so I mean it's kind of a

gross clip but it shows an important

point in the story and that the super

heroes aren't always nice guys

right running on water be Incredibles

[Music]

so let's say you want to run on water

you need an upward force to counteract

the gravitational force that pushes down

one way to do this would be kind of like

slapping the water if I hit the water

with my hand or foot then the water

pushes up on me but it's not a huge

force and it doesn't last for very long

I don't know I don't know how he does it

that means that you have to hit the

water really hard and then hit it again

really hard so you've really got to move

your feet back and forth super quick in

order to get this whole thing to work

you must have been booking how fast you

think you were Holly man I don't think a

normal person can do it but clearly –

can do it

[Music]

so when he stops and kind just hovers

there for a little bit on the water I

think it's the wily coyote effect so if

you remember wily coyote would chase the

he'd golf a cliff and then he'd say well

I just realized I'm now on the ground

and then he falls it's very dramatic and

it's kind of funny and I think that's

exactly what happens with – of course as

soon as he stops he would start sinking

into the water and fall down but it's

its comedic effect what are you waiting

for

[Music]

blind Ironman ready and three two

[Music]

in this scene Tony Stark is testing out

his Iron Man suit he had built one

before but it wasn't as sophisticated as

this one so he needs to make sure the

thrusters are configured properly to

allow him to fly so imagine you had like

a pencil and you want to hold it on your

hand right here and you're holding it

from the bottom if you push up it's very

easily just gonna tip over

and and so rockets from the bottom of a

device are a little problematic real

Rockets do this by having dimples on the

thrusters that can change the direction

very easily but there's another solution

and that's to have a higher thruster and

that's what Ironman does with this hand

when his hands are higher up then the

thrust is above the center mass and it

makes it much more stable and on top of

that he has his hand further apart from

his body and that further increases

stability in fact there's a guy that has

real-life Iron Man suit type flying and

he uses jets on his hands and it's much

more stable than putting them on your

feet so this is exactly how I would do

it if I was gonna do it impact force

guardians of the galaxy

[Music]

I'm not sure what exactly Groot does in

this case but if he stays completely

rigid as a rigid sphere then it's not

really going to help people inside now

if he has some type of I don't know in a

car we call it a crumple zone where the

car actually changes dimensions and

crumples up during a collision this

would increase the distance over which

it stops which would decrease

acceleration and it would make it more

survivable for the people inside another

aspect of this cage idea could be one to

protect from things like debris that

gets thrown around during the crash that

would definitely work I mean if you have

a shell around you and something comes

flying in that shell could block it it's

not just that you want wood to be strong

you definitely want it to be flexible

drew maybe he's like can pick maybe he

can pick what kind of wood he grows into

so he could make it both flexible and

strong depending on the situation

thank you see hoots the only one of you

who has a clue if I was Groot which I am

clearly not Groot I would have liked

things go down below the sphere that you

couldn't see and have those impact with

the ground first and have them kind of

be your crumple zone and then keep the

sphere rigid to protect from debris and

then you'd have a rigid part as a sphere

and then a springy part below for spares

the defenders

so in this scene from the defenders we

have Jessica Jones super strong and Luke

Cage super strong and when they punch

they really would have to consider what

angle they push at if I push with some

super large force then that same force

that can be applied to me because forces

come in pairs forces are always an

interaction between two objects so if I

punch horizontally the person could go

flying across the room but I'd go flying

back the other way and that may be

effective but it wouldn't look cool

there's a better way to punch if I was a

super-powered puncher and I punched up

then that person would push down on me

and I would get pushed into the floor

but I would not get pushed back so if

you're a super-powered person you can't

just go around punching like a normal

person you have to think about the

consequences of your actions but we

should probably all do that anyway just

look how you been I'm sorry x-ray vision

Man of Steel

[Music]

so this is the part where Clark Kent

starts to realize that he has powers and

one of those powers is x-ray vision

how does x-ray vision work I think the

first question is how does vision work

we see things because light reflects off

of them and enters our eye or maybe it's

a it's a light source itself but light

has to enter your eye in order to see

things x-rays are just another type of

light with that smaller wavelength than

visible light but in this case how does

Superman have x-ray vision is stuff

coming out of his eyes or stuff coming

into his eyes if x-rays are coming out

of his eyes he can't see them it's just

shooting out there are x-rays around

background radiation it's not very much

and that could pass through people's

bodies and he could see them but overall

it's definitely a problematic thing to

be able to see through people with just

rising wind up Avengers endgame

[Music]

so Captain America has Thor's hammer and

he's trying to hit Thanos he could just

hold the hammer and swing his whole arm

and hit him but by winding up the hammer

first it's going in a circular motion

the hammer is actually going at a

greater speed if he times just right his

arms moving up and the Hammers moving up

relative to the hand so that gives it a

much greater speed on impact with Thanos

his head so greater impact speed would

mean a greater impact force and

hopefully knock him down in this case

there's no real benefit to spinning at

multiple times except for the main

benefit that it looks cool and if you're

a superhero and you're in you know a big

battle number one you got to look cool

give me that conclusion I think these

are just great examples of even if

they're not real physics physics is

still all around us and we can find it

in the most trivial things even

superhero movies so physics in movies

I'm all for it even if it's not 100

percent correct because what if you did

have completely realistic physics and

superhero movies it might not be that

much fun we go to the movies now for the

correct physics we go there because they

don't have correct physics really and

and I'm fine with that

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