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Indiana Jones and nuking the fridge survival

by mauricem
Tags: fridge, indiana, jones, nuking, survival
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DaveC426913
#19
Feb29-12, 05:37 PM
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Quote Quote by Mech_Engineer View Post
Haha you're probably right, and he did land on a downhill slope after all... Still it's less plausible than say him jumping out of an airplane with an inflatable raft and surviving by using the raft as a parachute
Yeah.

With the parachute/raft, there are plenty of factors that can nudge it into plausibility.

With a refrigerator, you have precious few physics principles at play. Ballistic flight is ballistic flight.
mauricem
#20
Mar2-12, 03:27 PM
P: 17
So, I found a helpful article here http://www.overthinkingit.com/2012/0...view/?page=all that answered a lot of questions. But, I have a couple more. In one part the author says Indiana's speed was 38.32 m/s
"Assuming the Soviets are attempting to escape the advancing plume at their vehicle’s maximum speed (~80 mph, or ~35.76 m/s), we estimate Indy’s horizontal velocity to have a total magnitude of approximately (2.3 m/0.9 s + 35.76 m/s) = 38.32 m/s."

I tried to use that to estimate how far he flew from the video. It takes him 19 seconds to launch till he hits the ground on his first bounce (assuming the film is real-time). That means he flew 728.08 meters which is way short of the minimum 2.0 km he would need to stay out of the Lethal total dose (neutrons and gamma rays) range of 1.4km for a 20kT explosion. Much less the 4.2 km he'd have to be to keep from getting third degree burns.

Is my math off or can we assume I'm missing something?

Can we determine how far away he was from the explosion using a plume height of between 30 to 40 feet (again based on 20kt) and the final image of him watching the cloud?
mauricem
#21
Mar2-12, 03:28 PM
P: 17
Quote Quote by gulfcoastfella View Post
keep in mind that the only thing George Lucas ever hears these days is "yes, it's possible".
Lucas says, "Will the new Star Wars be good?" Everyone says, "Yes, it's possible." LOL
mauricem
#22
Mar2-12, 03:28 PM
P: 17
Quote Quote by Hologram0110 View Post
I'm assuming that you are in this forum because you want to know about the likeliness that radiation would kill him. Death by acute radiation poisoning requires quite a bit of radiation. Most of those who do die of "acute' radiation doses live for around a week and become weak/sick slowly over that time. To die from radiation within minutes you need much more radiation than would kill you over a week. Based on the movie I will assume that he got so little radiation he didn't even get sick from it.

A fridge would shield you from alpha and most beta. If it were lead lined it would shield you from pretty much all alpha, beta and low energy gamma. Some of the high energy gamma would still get through.

Now the highly scientific way of doing this would be to get a radiation spectrum from a nuclear blast and then use software to calculate how much of that would make it through lead box with 1 cm lead. I think this might be a bit beyond the scope of your blog.

You might just want to look at the radiation dose from gamma at a certain distance and then assume that some percentage of that is blocked. Then look at the survival rates for someone who absorbed that much radiation.
Is there a good site to get that kind of infomation? I haven't found any.
mauricem
#23
Mar2-12, 03:32 PM
P: 17
Quote Quote by Rive View Post
Judging by the scene at 60 seconds, the distance of the willage to the centre of the blast was ~2-3 km.

Here: http://www.nukefix.org/weapon.html I could find some pictures from real tests. In section "Wood-framed homes" there are two pictures related to a test of "250 Kt, 2.65 miles" which are quite fit for the immediate effects seen in the movie.

For the calculation of the immediate radiation effects I've found this: http://www.fourmilab.ch/bombcalc/
If I read it right, for 250Kt and 3 km it suggests only 10 rem, so no immediate effects from gamma or neutron radiation.

(Fallout is a different matter: I welcome any link for the following, 'shower' scene :-) That face is priceless.)

So what remains are:
- the mechanical damage by the flying/landing
- if the fridge can insulate thermal part of the initial blast
- at the landing point of the fridge the land was still on fire: the temperature can be still too high to survive.
Great numbers. I hadn't noticed the fire in that last scene. I'll have to watch it again. That means he was at least within 2-3km of the blast zone. I'll use a starting point of 2.6 miles.
mauricem
#24
Mar2-12, 10:43 PM
P: 17
My math was off. I forgot about the 200-300m from the bomb to the house. It's still not enough, but a little better.
mauricem
#25
Mar7-12, 11:01 AM
P: 17
Here's my final analysis. I hope someone can check my numbers.

1 Jones Gets in the fridge
Indiana Jones is in a nuclear test town when he hears a siren. The Russians flee the town in a car. He spots the only commercial lead-lined fridge ever made, presumably for nuclear food safety tests. He climbs in, puts on a neckbrace from his bag and gets in crash position. He's now ready for his "magic carpet ride."

2. Explosion
The 20kT nuclear bomb explodes. The atmosphere, plus the walls of the home and 1 cm of lead shielding, protects him from all alpha, beta and low energy gamma radiation. Some 5 rem of high energy gamma gets through. This is within the "safe" limits of radiation exposure of 50 rems. The heat from the fireball causes a high-pressure wave of highly compressed air to develop. The front of the blast wave travels rapidly away from the fireball and launches the fridge into the air.


3. launching
In the air, flying at 38.32 m/s he feels a force of 46.2 G. The horizonal force to his body drains the blood to the lower parts of his body. He stops breathing because his ribs and internal organs empty the air from his lungs. The average person can hold their breath for 1.40 seconds, but Jones easily holds it for the 20 seconds he is in flight thanks to his college history classes. Small cracks in the fridge let some superheated air in, but it mixes with the cool interior and lowers the temperature. Having survived the heat of the Temple of Doom he is comfortable. The Russian car, going 80 mph, is destroyed by the air blast wave, but Jones fridge accelerates plast the blast.

5. landing
19 seconds later and at 1028 meters away the fridge descends to the ground. Realizing he is about to land he flattens his body against the fridge wall. Jones hits the ground with a force equal to slamming into a brick wall at 100 mph. Thanks to his neckbrace and crumple zones built into the fridge by Army engineers he is able to withstand the shock.

He takes off his neckbrace and climbs out. Looking back, he enjoys the view of the the mushroom cloud like a New York tourist. He is scrubbed down to remove the latent radioactive material. His exposure could cause possible late effects, like chromosomal or eye damage. We'll have to wait till the sequels to find out.
DaveC426913
#26
Mar7-12, 11:59 AM
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So, not really an analysis; more like a detailed synopsis?

One bit of confusion with these numbers:
The average person can hold their breath for 1.40 seconds, but Jones easily holds it for the 20 seconds he is in flight thanks to his college history classes.
mauricem
#27
Mar7-12, 01:42 PM
P: 17
I guess not an analysis since that was done by overthinkingit.com. I just want to make sure some of my math holds up. I'll break that out of the synopsis for ease of viewing.

A 20kT nuclear bomb (Based on the 1957 Operation Plumbomb testing) would emit 10 rem of high energy gamma radiation at 300m. 1 cm of lead would provide a 50% drop. The calculation of rem is based on Rive's comment even though it's nuch larger. I admit I can't find a reliable gamma radiation exposure calculator like Hologram0110 suggested.

A body flying at 38.32 m/s feels a force of 46.2 G.

Hitting the ground at that speed would be like hitting a brick wall going 60 mph (thanks QuantumPion)

The college history class is a joke, but the record is 14 minutes.

I did hit a snag. According to Wikipedia, a kT explosion would result in Thermal radiation effective ground range of 2000 m. Meaning Jones would literally be standing in the middle of a firestorm. He would have to be at least 4000 m away just to get away with third-degree burns. So, we can assume he was immediately burned to a crisp when he got out of the fridge?
http://en.wikipedia.org/wiki/Effects...ear_explosions
cmb
#28
Mar7-12, 01:48 PM
P: 628
Quote Quote by Mech_Engineer View Post
The most ridiculous part of the scene isn't hiding in a lead-lined fridge. ...
The really ridiculous part is him being thrown miles by the blast, falling hundreds of feet, and surviving inside the fridge.
Fully seconded. The closed fridge would mitigate all the main immediate effects - pressure wave, intense IR, it would even allow the air he was breathing to remain at a tolerable temperature for long enough.

The fall in a fridge onto sand would be a shock deceleration in the 100's of G range, whereas ones internal organs rip out of place at much over 30g, or less depending on your age/health. I think aircraft are required/designed to withstand 22g. Not much point making them stronger than that.
Mech_Engineer
#29
Mar7-12, 01:59 PM
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Quote Quote by mauricem View Post
A body flying at 38.32 m/s feels a force of 46.2 G.
This isn't true because Indy wouldn't be accelerating at 46.2 G for the entire flight. He would be accelerated by the blast, presumably to some terminal speed in the blast wave, and then follow a projectile trajectory. So for most of the flight he would be basically weightless.

Additionally that speed is way short of what would be required to throw him the distance shown in the time shown. Since he's traveling on the "front" of the blast wave in the movie, he would have to be travelling at the speed of the shock wave from the blast (e.g. the speed of sound). The movie shows him overtaking the car at what appears to be somewhat less than 750 mi/hr, but he'll be travelling a whole lot faster than 85 mi/hr... maybe 150-200 mi/hr (70-90 m/s).

I also take issue with the "hitting a brick wall at 60 mi/hr" also. He appears to be flying in a low incident angle projectile arc with a maximum altitude of maybe 200ft. If this is the case his vertical speed when he hits the ground would be about 77 mi/hr presuming freefall, and that completely ignores any horizontal speed (which is very significant). I would say 100 mi/hr minimum. There are some slight mitigating factors like the downward slope he lands on, but it there are a lot of intensifying factors as well.

Of course, let's not forget that fridge is probably one of the heaviest things in the house, and therefore least likely to be thrown a significant distance... we have to just ignore that fact.
cmb
#30
Mar7-12, 02:02 PM
P: 628
...but why let the truth get in the way of a good story. I liked the film, but it's not as if I am going to believe there are telepathic glass skulls that would.... well, no need to spoil the film for those who've not seen it....!

The bit of mad science I had a particular problem with (is this a thread diversion, or best to keep 1 film per thread!??) was the warehouse scene and the idea that a magnetic field could be so strong that it could accelerate metal shot through 10's of metres of free space, yet didn't cause other 'issues' for metallic parts as they got closer. I think mag fields are approximated as r^-3, and effectively diminish to nothing once the magnetic energy of the surrounding free-field spaces reaches some level determined by the magnetic material. If the magnetic fields generated by the skull really were that strong (enough to influence a paramagnetic material like gold), then there's no way the rest of the film could've worked out. Anyone who came close to it, I expect their blood (on account of the iron-bearing haemoglobin) would've behaved like a magnetorheological fluid!!!
Mech_Engineer
#31
Mar7-12, 02:10 PM
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Quote Quote by mauricem View Post
Can we determine how far away he was from the explosion using a plume height of between 30 to 40 feet...
The plume height will be in thousands of feet, not sure if you missed that. Early in the blast it would probably be in the range of 1000-2000 ft, but it would rise to a final height of maybe 30,000 ft.
Rive
#32
Mar7-12, 02:43 PM
P: 357
Quote Quote by mauricem View Post
I did hit a snag. According to Wikipedia, a kT explosion would result in Thermal radiation effective ground range of 2000 m. Meaning Jones would literally be standing in the middle of a firestorm. He would have to be at least 4000 m away just to get away with third-degree burns. So, we can assume he was immediately burned to a crisp when he got out of the fridge?
Fortunately (unfortunately?) no. The effective range of the primary thermal radiation is one thing, but that radiation ends within seconds (as the pure explosion plasma extends and covered by the much colder mushroom cloud). After that the temperature and the thermal radiation converges to the temperature of the environment, which will be much less and - depending on the distance - maybe safe.

Other point is, that the upstream of the nuke will suck in fresh air on ground level which will start cooling the temperature rapidly.

When Mr Jones got out of the fridge some plants on the ground were still on fire (but not destroyed entirely by the previous thermal radiation). This possibly means inconvenient but still survivable conditions.

Ps.: I still think that the distance of the town to the nuke was more than few hundred meters. I understand that this not fits with the effects of a historically correct 20kt bomb in the assumed range, but in case I have to choice the field of the error between historical and observed (erm...) then I will accept the observed and assume the historical error :-)
mauricem
#33
Mar7-12, 09:43 PM
P: 17
Rive, my man. I hadn't thought in terms of time. You just saved my post. What distance do you think the town was from the blast? I'm open to suggestions.
mauricem
#34
Mar7-12, 10:06 PM
P: 17
Prefect breakdown. Thats exactly what I was missing. I did think he was traveling the speed of sound, but thought that would mean he was going the same speed throughout. That would mean he was traveling at amazing rate of speed. Hitting a brick wall at 100mph would be pretty nasty. Assuming, of course, a lead fridge could even fly. ;)
mauricem
#35
Mar7-12, 10:53 PM
P: 17
Quote Quote by Mech_Engineer View Post
The plume height will be in thousands of feet, not sure if you missed that. Early in the blast it would probably be in the range of 1000-2000 ft, but it would rise to a final height of maybe 30,000 ft.
Missed some zeros. Thanks MechEngineer.
wizwom
#36
Mar13-12, 08:01 AM
P: 71
The initial acceleration figure you are giving is assuming all the force is a single jerk. Fluid mechanics (which is the force exerted on the fridge) don't work that way.

During the passing of the blast wave, the fridge would lift due to surface effects, and until it lifted, the fridge likely tip, since one could assume its friction force would easily overcome skidding. Once it lifts, it would have sail effects propel it horizontally.

The fridge, due to aerodynamic effects, would present is smallest surface to the direction of travel, so it would end up horizontal.

On the landing, the horizontal velocity would not be counted; the vertical speed (mostly from the aerodynamic surface lift while the fridge was still on the ground) would be the force there.

At no time in all of this would there be great forces; hitting the ground would be like a fall from the fridge's maximum height.


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