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  • Diandra Leslie-Pelecky: I thought that was really creative

  • and totally possible.

  • My name is Diandra Leslie-Pelecky.

  • I have a PhD in physics, and I started off my life

  • as a condensed-matter physicist working in nanomedicine.

  • Along the way, I ended up writing a book called

  • "The Physics of NASCAR."

  • So today I'm gonna use that knowledge

  • to talk to you about some clips

  • from "Fast and Furious."

  • This is one that is a little difficult to analyze,

  • because you're not quite sure how long they're falling.

  • It could be anywhere from 11 seconds to maybe 15 seconds.

  • That's a really long time to fall.

  • I calculated out

  • what Dom's terminal velocity would be,

  • and that's biggest velocity you can fall

  • given that drag gets bigger as the speed goes up.

  • And he almost approaches it.

  • After 11 seconds,

  • Dom would be going 124 miles per hour

  • when he hit the water.

  • He would have fallen about 1,775 feet

  • at that point.

  • Now, 124 miles per hour into water,

  • maybe that's survivable.

  • Laso Schaller holds the record for the highest jump.

  • That was from 193 feet.

  • He hit the water at 76 miles an hour.

  • He broke his right clavicle and dislocated his pelvis.

  • The Golden Gate Bridge is about 245 feet.

  • People hit the water at 86 miles an hour.

  • Only 5% of the people who jump survive.

  • So the probability of them surviving is pretty small.

  • They built a launcher and took this beautiful

  • 1966 Corvette and actually launched it

  • off the side of the cliff,

  • and then they had stuntmen

  • who did it separately from the car

  • because being hit by a car midair

  • would be worse than actually hitting the water.

  • And so they had the stuntmen do it,

  • but the stuntmen were on cables.

  • Then they came back, did it on a green screen

  • with the actual actors, who were, you know,

  • maybe eight feet above the ground.

  • But this one I think I would have to give a score

  • of two, because there's absolutely no way

  • they could've survived a jump that long.

  • So, this a 1969 Camaro.

  • It's got a mass of about 3,500 pounds.

  • So, they're hitting 90, so you know

  • the boat's going at least 90 miles an hour.

  • One of the things that you notice is that

  • when the car and the boat are both speeding along,

  • they're parallel to each other.

  • Now, how they all of a sudden get behind the boat,

  • I'm not actually sure how that happens.

  • But let's assume they can do that.

  • When they take off, they're going at approximately

  • 45-degree angle off this ramp,

  • and they're going 120 miles an hour.

  • So not all of the speed

  • is taking them in a horizontal direction.

  • So I've taken cosine of 45; they're only now going

  • about 78 miles per hour toward the boat.

  • Now, that's a problem,

  • because the boat and the car looked like

  • they were going the same speed.

  • And the problem is, if the boat's going 100 miles per hour,

  • it'll be 1,200 feet from the shore.

  • The problem is, the car can only go 945 feet

  • in the time it's in the air.

  • There's actually no way

  • that the car could make it onto the boat.

  • Let's pretend the boat is only going 78 miles an hour,

  • because if they are, it's totally possible.

  • It is going fast enough, and it makes up

  • all the distance between it and the boat.

  • So if you include drag,

  • they're gonna lose some of their speed

  • due to air resistance.

  • They're still gonna hit that boat

  • at around 105 miles per hour.

  • The kinetic energy of the car

  • and the guys in the car, at that point,

  • is equal to about a fifth of a pound of TNT.

  • Some of that goes into wrecking the boat

  • and wrecking the car, but not all of it.

  • Which means some of it is gonna go into the guys,

  • and they're gonna have a whole lot worse

  • than a broken arm.

  • I think I'd give it probably a seven out of 10,

  • because it's possible it could happen.

  • They had to modify this tank

  • so it could go 60 miles an hour,

  • 'cause they normally only go 30 miles an hour.

  • Dom, we'll assume his car was going 60 miles an hour,

  • so when he left it, he was going 60 miles an hour.

  • So you can look at conservation of momentum

  • and figure out that by the time they hit and continued on,

  • they were probably going around 40 miles an hour.

  • So a little bit of change in speed,

  • but the problem is when he hit the car

  • going 40 miles an hour, and she is about 120 pounds,

  • he's about 225, so you're talking about 340 or so pounds.

  • You're gonna be hitting it with an acceleration

  • of almost 100 g.

  • They have no protective gear.

  • So, you know, race-car drivers

  • routinely survive hits of 100 g.

  • They've got a big car around them.

  • And maybe it's possible that Dom could launch himself

  • at just the right angle to intercept Letty.

  • And then maybe it's possible that

  • that path took you onto the second bridge

  • instead of over the first one,

  • and maybe it's possible that there happened to be a car

  • at the point where they were landing,

  • and maybe it's possible

  • they survived hitting the car together.

  • Each one of those things might have happened,

  • but all four of them together

  • is just too much of a coincidence.

  • Once you're in the air, you cannot steer.

  • So if you misjudge in any way,

  • you're gonna miss her.

  • Now, if you watch baseball players,

  • they develop this very intuitive ability

  • to know the arc of a ball.

  • And after all, it's just a parabolic motion.

  • Maybe just Dom understands physics so well

  • that he knew exactly where to launch himself.

  • And if you talk to a race-car driver,

  • they would be able to understand centripetal acceleration

  • and explain it to you. Again, no equations,

  • but they get this intuitive understanding for it.

  • So, it's just possible, maybe Dom has

  • rescued enough people who are flying through the air

  • that he understands how to do it.

  • Hollywood has its own physics.

  • One of the rules is they have time dilation,

  • which is that when something really exciting is happening,

  • it can take as long as you want it to take.

  • Slowing down, let's say 120 miles an hour,

  • and I pick that number only because

  • that'll tell you, at 120 miles an hour,

  • the car is going two miles every minute.

  • So for every minute of that clip,

  • you're traveling two miles.

  • The longest airport runway in the word is 3.4 miles,

  • which means if they were on that runway,

  • this still could take 1.7 minutes.

  • And it doesn't.

  • It takes a lot, it takes, like, 11 or 12 minutes,

  • which would result in just this unfathomably long runway.

  • OK, so Dom is driving a 2012 Dodge Charger,

  • and let's pretend this is a super-reinforced version

  • of a Dodge Charger.

  • He doesn't have a lot of time to get up speed.

  • Because he's only got the inside of a plane,

  • and as you saw from the fight that was going on,

  • there's not a lot of room.

  • I think I have to give a one.

  • Just because here,

  • they stretched my ability to ignore reality

  • just a little further than I'm capable of doing.

  • Try to figure out how much that vault weighs,

  • according to the storyline.

  • So, we're gonna assume it's a 5-ton vault.

  • That's about 10,000 pounds.

  • There's $100 million in $100 bills.

  • That's gonna give us another 2,200 pounds.

  • Dom is 225 pounds,

  • and the car is 4,180 pounds.

  • That gives us a total weight of 16,605 pounds

  • that his car has to accelerate.

  • If you ever tried to move something heavy,

  • like a refrigerator or a bookcase,

  • you push on it, and it doesn't move.

  • And you push harder, it doesn't move.

  • And you push harder, and finally it moves.

  • That moment when it moves,

  • you've just overcome the static frictional force.

  • The static frictional force is higher

  • than the kinetic frictional force.

  • And what that means in real-people talk

  • is that once you get something moving,

  • it's much easier to keep it moving.

  • So the question is,

  • is it possible for this 2010 Charger SRT

  • to overcome the friction needed to move?

  • So we're gonna calculate how long it would take him

  • to accelerate up to 50 miles an hour.

  • We've got the 425-horsepower car

  • accelerating 16,605 pounds.

  • And it turns out that would take about 5.86 seconds,

  • which is a little longer than it took him

  • to actually do it in the movie.

  • So the fact that he got the car accelerating that fast,

  • that definitely couldn't happen in real life.

  • But that's without friction.

  • So once you put friction in,

  • what you find if you calculate

  • is that the coefficient of friction between, like,

  • steel and asphalt is pretty high.

  • And you probably could not,

  • even with a nitrous oxide boost,

  • get the vault moving.

  • So, once you got it moving, you could keep it moving.

  • What the folks have said who did this stunt,

  • they found the same thing.

  • They learned a lot about static friction the hard way.

  • And they actually put a slippery material

  • on the bottom of the vault to get it moving.

  • But one of the problems with that

  • is when you make something easier to start moving,

  • you also make it easier to stop moving.

  • And my understanding is they were very surprised

  • when they thought it would come to a stop

  • and it took a lot longer to stop than they thought it would.

  • The other thing is the question of,

  • you have this fairly small mass of a car and Dom.

  • That's about 2,000 pounds.

  • And the mass of the vault,

  • which is about 15,000 pounds.

  • So you've got something that's seven times bigger

  • than something else.

  • Now, think about when they're coming down

  • and then Dom starts, stops, and he lets the vault

  • sort of swing around.

  • The vault is, you know, seven times heavier

  • than Dom and his car.

  • And I just don't buy that he has enough traction

  • to swing the vault without the vault pulling his car along.

  • Making these stunts work in real life,

  • with practical effects and not CGI,

  • so they built something like seven or eight different vaults

  • with different weights so that they could do

  • all the different parts with the vault.

  • And in fact, in some points, they actually had

  • a little semi cab inside the vault

  • and the vault was driving around by itself.

  • So I would give this stunt a five.

  • I mean, we've all tried to go up a down escalator, right?

  • That's all he's doing there.

  • This whole stunt relies on

  • the person being able to run faster

  • than the bus is falling.

  • When they filmed this, the stuntperson did actually

  • run up the bus as it was falling.

  • I had some real questions, because

  • it's not like you're pushing off something solid.

  • You're pushing off something that's moving

  • in the other direction.

  • It spun around to be in exactly the right position