Sunday, November 22, 2015

Interstellar

Space! The Final Front... wait a moment,

I'm sorry Dave, I'm afrai.... no, not that one,

So, in some ways this movie, Interstellar, reminds me a lot of other space movies we have watched this semester. Though the resemblance is much closer to 2001 than Star Trek. Where Star Trek goes to great lengths to appease fans and Hollywood rather than physics, 2001 and Interstellar went to great lengths to keep the physics intact, with only minor gimme's for Hollywood's sake. Of course, that is ignoring the whole, "Fall into a black hole, discover it is a created 3-D tesseract designed by super advanced humans some indeterminately long time in the future just to make sure Matthew McConaughey got to send a message to his daughter that saved the human species" ridiculousness. (Time paradox anyone?)
Ow
But, Kip Thorne worked hard to make sure the movie was as close to physically accurate as possible, and he did a good job. One of the most fascinating parts of the movie to me was the planet referred to as "Miller's planet", after the explorer that landed on it. Orbiting close to the super-massive black hole called Gargantua, there were many oddities about this planet as a result of it's orbit. The first one, is the passage of time on the planet. Being that close to a black hole, the gravity of the black hole causes time to run slower on the planets surface than away from the black hole. According to the movie, one hour on the surface of the planet is 7 years back on earth or on the space ship.
Location of Miller's orbit


In Kip's book on the physics of the movie, he states that in order to have that much time dilation, The planet has to be incredibly close to the black hole. We already knew that, but Kip goes into a bit more of the implications there of. So, in the movie we see the giant waves that seem to circle the planet and pass by any given point once every hour, based on time given in the movie.
Ouch
These waves dwarf any waves we have ever seen on earth. For comparison, the largest wave seen on earth was 100 feet tall. These waves are estimated at around 4,000 feet tall. So, it seems pretty obvious that these waves are caused by Gargantua's massive gravity, which is why they dwarf our own waves, only created by the gravity of the moon, which is minuscule by comparison. But a good question to ask is exactly how they are formed. Well, the first part of the puzzle is realizing that Gargantua pulls Miller into the shape of a football, like so:
Any one up for some handegg?
As you can see, this causes massive bulges on the planet, which is why most of the planet is only about knee deep with water. However, assuming the planet is tidally locked to Gargantua (which is necessary for the planet to not shake itself apart), why do the waves move? Without the planet rotating, the "waves" would just stay in place, making a really awesome planet wide ocean that is about knee deep at the equator, and thousands of feet deep at the poles. And while that would be awesome, and more habitable than the reality, that's not how the planet is depicted in the movie.

Instead, Kip proposes the planet is tidally locked to Gargantua, but rocks back and forth. If this is the case, then a possible explanation is a phenomena called tidal bores. In essence, tidal bores are what happens when the tide changes rapidly enough or with enough force to create waves that move with the tide. On earth, these are at times spectacular, but rarely devastating or dangerous to those outside of the flow of the water. However, a tidal bore caused by Gargantua's massive gravity, could result in the massive, 4,000 ft tall waves every hour.
Tidal Bore on Earth
Finally, there is an interesting observation that Kip makes in his book. If we make an assumption that Miller's planet was formed while the universe was still young, say around 12 billion years ago in Earth time, then following the time dilation of Miller, then at "present day" when Cooper & co make it to the planet, it is only 200,000 years old. It is interesting to think that they could have set foot on a planet that in the universal sense is incredibly young, and undeveloped. That's some time travel crap right there.

Sunday, November 15, 2015

Star Trek (The Reboot)

And what a reboot it was. Even though I never was a trekie, and haven't really watched any other Star Trek stuff, and am completely unqualified to make that statement, I just want to say:


Now that the silliness is out of the way, I want to approach two of the technologies in Star Trek, why they are unfeasible, and why they were necessary for the over all plot of the movie. Aka, why Kirk and Spock would not have bravely defeated Nero without:

1. Warp Drive!!!!!!
So. The idea of Faster Than Light travel is nothing unique to Star Trek. Basically every sci fci universe worth it's salt has some form of FTL woven in somewhere. The way Star Trek's works is generating large amounts of energy through the reaction of deuterium with anti deuterium (matter with antimatter), using the reaction to produce highly energetic plasma, which then was used to create a warp field, which encompassed the ship, allowing the ship to enter subspace and move at "warp speed" aka very very fast.

I see several problems here. Do you? Even ignoring the whole antimatter thing (supposedly controlled by dilithium, which is non reactive with antimatter when put inside an EM field.... wat?), there is the whole underlying issue that according to Einstein, nothing moves faster than the speed of light. It just can't happen. However.... It is undeniable that warp is central to the entire concept of a "star trek", let alone the movie Star Trek. 

To explain why, lets do an example. Take the distance from Earth to the Moon. Something humanity has already traveled, so its something we can somewhat wrap our heads around. Hop in your BMW (cause who cares about emissions in space?) and drive your way to the moon (just bare with me, its an example, I'm suspending the non-relevant laws of physics) and lets see how long it takes you. Well, the distance is 384.4 million meters. That is 3.84 x 10^8 meters. Let's be generous and say you are driving your BMW on a German Autoban pointed straight at the moon, and you floor it. The BMW i8 has a top speed of 120 km/h. In meters per second that is right around 70 m/s. So you make it to the moon in.... 63.5 days.

The actual Apollo 11 mission that first made it to the moon made the trip in around 3 days. For a faster spacecraft, hop in the New Horizons spacecraft, which hit speeds of about 15730 m/s, and you make the trip in just under 7 hours.

Light would make the trip in... 1.28....... seconds.

In order to do the type of exploration and travel that happens in the Star Trek universe, where distances between stars are measured in light years, or 9.461e+15 meters, we have to move faster than the speed of light.

The other technology I have an issue with is:
2. Transporters

The way transporters work is they essentially deconstruct a person, convert them into a data packet, shoot the data packet at a destination and recreate them on the molecular level at the destination. 

Besides the obvious technological and physical issues with this tech, I want to draw attention to a moral one: if we actually did this in real life, would the person reconstructed on the other end really be the same person? Would breaking someone into their constituent molecules, turning those molecules into data, and then undoing the process on the other end produce the same living being with all the thoughts, emotions, and personality of the original? 

And if the answer is yes, then it raises another question: are we more than a sum of our pieces? If someone took a collection of atoms and organized them in the exact same configuration as your body, would that new collection of molecules actually be you? It is a frightening thought, one that touches on the very nature of what makes us living creatures.

Now, as far as the plot is concerned, teleportation (as that is from a non-sciency stand point what transporters are) is probably one of the most convenient, widely useful, and profitable abilities ever. Imagine, being able to be at school, realize you forgot your super important, final grade determining paper at home. No more lame excuses, just walk over to your transporter, beam home, and grab it. On the flip side, if you are driving your spaceship full of red matter in a suicide rush at the big baddy's ship, but don't want to die, just have your friends teleport you back to your home ship, safe and sound. What could possibly be not to love about transporting?

Sunday, November 8, 2015

Fat Man and Little Boy & Gojira

This week we had a double feature, watching the movie Fat Man and Little Boy and the original, Japanese Godzilla. The commentary was very evident, and both sides of the story were shown, questions were raised, and moral questions left unanswered.

In Fat Man and Little Boy, the scientists near the end of the movie slowly face a realization of the magnitude of the project they are working on- a device that could easily kill thousands of people with basically the flip of a switch. As they realize how dangerous and deadly this device is, they start to dig their heels in, try to back out or provide reasons for why there was no need to use it. Eventually however, as we know, they do use it, the world finds out about it, and an arms race begins that plunges the world into the First Cold War. Men such as Oppenheimer created the tool that would shape much of war for the next millennium and beyond.

In Gojira, the scientist Serizawa creates a devastating object, called the oxygen destroyer, that removes all oxygen from water, ruining the ecosystem and eradicating all life inside that patch of water. When the monster Godzilla shows up, he at first refuses to use his weapon, for fear that others would discover it and use it for terrible things. Eventually, he agrees to use it, but he burns all his notes, removes all evidence to how it was built, and even sacrifices his own life to make sure no one can learn the secret to how it was built. 

In both, the scientists worry about the consequence of the usage of their weapon, however in the end they decide that the benefits of using it out outweigh the risks, and that there is no other option.

I have often thought about creating weapons for the military to use. I am a strong supporter of the military, and feel that they are our bastion of defense against those that would threaten our way of life. Knowing that my tools could be use to protect the lives of American soldiers and civilians would give me pride in my work, and make me feel good knowing I was able to help others and my country. We live in a world where our enemies are many, unwavering, and ruthless. We have to be the same to stand up to them. As long as we keep our humanity in the process so we can separate ourselves from those we are fighting.

Sunday, November 1, 2015

Day After Tomorrow

Alright, this movie actually made me laugh. Multiple times. For those of you wondering, Day After Tomorrow is actually an amazing movie, and well worth the watch. If you go in expecting a comedy. If you go in expecting a super accurate physics representation of global warming, the end of the world, and temperatures falling at 10 degrees a second.....

However, this week I won't be evaluating the physics of this movie (which is a shame, there are so many great places I can go with "10 degrees a second"). Instead, I will be talking the problem of global warming. Specifically, How does the modern rise in temperatures compare to historic fluctuation in global temperature. Surely everyone remembers learning in elementary school about the ice ages and the mammoths running around every where. And that one land bridge in the Bering strait that they always thought was so important to teach everyone. So clearly the planet has had some cool points, and seems to be in or on its way towards a hot point now. How does this look throughout history?

Well, Humanity as a species started taking measurements of the global temperature all the way back in the 1880's. Unfortunately, I was only able to dig up records dating until the 2010's, but it still should give us some sort of an idea, right?

From NASA's records

OH DEAR GOODNESS WE ARE GOING TO DI..... wait, the entire y-axis covers only 2 degrees Celsius. However, the global temperature is right around 0 degrees Celsius according to NASA. If one of the scary things about global warming is the polar ice melting, ice melts at 0 degrees Celsius. Obviously, the poles are cooler than the global average, that is what an average is after all. But if you start increasing the global average, the poles will increase too. Eventually, the poles hit 0 degrees Celsius and then....

So, that is only dating back until 1880. We know the ice ages were a bit further back. So how are we supposed to know what the temperature is before we took measurements? We can actually estimate what the global temperature was using clues from things such as tree rings and other proxy data sources. You take a bunch of proxy data sources from as far back as we can figure and put them together, and you get something that looks (something) like this:


Ok, so the scale on this graph is a bit bigger, but it points out an interesting note: The Earth seems to have been hotter, much hotter, in years past. Considering best evidence dates humans anywhere from 200,000 to 10 million years ago, we as a species likely didn't live through the incredibly hot temperatures, however there is a chance we have lived through temperatures hotter than the current ones. What does that mean for modern man and global warming? Well, I leave that to someone smarter than myself.

P.S. in case you were wondering, in 3015, global warming has not ended humans. Not to say it won't, but so far we are still kicking.

P.P.S. Why on earth is the movie called "Day After Tomorrow"? It never references that line at all, the whole movie takes place over a week or two, and just in all ways the name seems ripped out of nowhere. But whatever.



Sunday, October 4, 2015

2001: A Space Odyssey

The month is September. I think. Someone else thinks it's early October. It's hard to tell anymore.

This week, I will be doing something a bit different. We watched 2001: A Space Odyssey, and rather than comment on some specific part of it's physics, I will be just reviewing the movie as a whole. I will be reviewing the individual components of the movie on a 10 star rating scale, then give my overall score on an out of 100 scale.

It's hard to know exactly where to start with a movie this long, with this much of a reputation. So let's start basic: Cinematography. The various landscape shots included are beautiful, even considering most of them are of outer space. The vistas pictured during the Dawn of Man segment were just wondrous, and throughout the movie the shots were varied and plenty. Several of the scene transitions were amazing, particularly the one where the club thrown in the air (the first weapon) transitions to a nuke orbiting the earth (the ultimate weapon). The long cuts used by Kubrick did a wonderful job of establishing both the importance of the actions of the cast (credit to Tilman for pointing that out to me), as well as give a sense of vastness to the epic. The closing segments, the acid trip through the stars and the scenes in the bedroom, were both wonderful pieces for vastly different reasons. The trip through the stars was an assault on my senses, with lights passing by faster than I could process. While it was overwhelming, following a movie with little color or action, this scene really sets itself apart and shows itself as a well crafted, if overstimulating, scene. The immediately following and closing scene in the bedroom features numerous long shots, perfectly positioned to highlight exactly what Kubrick wanted you to look at. The cuts are well done, and each one leaves you slightly more in awe (and confused) as to the goings on of this room.
Even with all of these things, there are a few critiques. A few of the cuts are rough (he broke the 30 degree rule, how could he?), there are several cases of obviously reused shots, and some of the shots are just way too long. Overall though, Kubrick does a great job. 9 stars for the beautiful camera work
This isn't even close to as weird or trippy it gets.


The next thing that jumps out at me watching this movie is the sound, or in a lot of cases, lack of it. There are 24 minutes before the first spoken dialogue, and 23 minutes after the final spoken line, plus some other scenes, there are 88 minutes of dialogue free movie, in the entire 160 minute run time. In many movies, this would be a bad thing. However, Kubrick's skillful use of the absolutely beautiful orchestral score, spot on sound effects, and tension filled silence leads to several extremely haunting segments and really powerful moments, really using the lack of dialogue as an advantage. A solid 10 stars for the wonderful work.
In space, no one can hear you scream.


Oh HAL. Beautiful beautiful HAL.
Now, characterization. Aside from HAL, who I will get to in a moment, the characterization was weak in places, and incredibly over done in others. We are introduced to the doctor in the second act, and told multiple details about him that are hardly relevant in the first place. that kind of lead up is typically reserved for a character we are supposed to care about, but would struggle to without these small details. Well, this doctor doesn't have a tragic or heroic death, doesn't really do anything where caring about him more than normal would influence the audience. On the other hand, Dr. Poole is viciously murdered by a rampant AI, and the only major characterization we get of him is a short phone from his parents for his birthday. On the other hand, there is HAL. For a robot, I actually found myself growing to like him, and actually feeling a little sorry for his death, thinking he truly felt remorseful for his actions. He really was scared of death. While I want to give 10 stars just for the beautiful characterization of HAL, unfortunately the shortcomings of the others I can only give 3 stars. All of them for HAL.

One of the most tugging and memorable character deaths
I've seen. And it was an "unfeeling" AI.

Now for the physics. I hesitate to judge the physics of this movie, as they are regarded of some of the greatest space physics in movies. However, I have mostly good things to say. First off, the depiction of the "zero gravity" of space was really good, the floating pen near the beginning the 2nd act was awesome. I have to say, grip shoes were a hilarious though believable touch. Unfortunately though, I take a star off for the slow crawl around the circular hallway though. She is able to float, just pick up your legs, tuck, spin, and set your feet down on the other side. Soooo much faster. After that though, the fact that Kubrick showed a realistic usage of artificial gravity - the spinning of the ship - shows he really paid attention to detail. He has not one, but two different space craft that make use of angular acceleration to create artificial gravity. Overall I am incredibly impressed with his attention to detail. One of the only major knocks against his physics was that the people walking on the moon were able to do so normally, however that is minor as this was before the moon landings, Kubrick couldn't know for sure how people would have to walk on the moon. 7 stars after the penalty for his great attention to detail, accounting for a few slip ups.
The running scene from a fixed camera position


Overall, the movie was incredibly enjoyable, and I loved watching it. All of the elements came together really well for a great, though confusing movie. With the ending raising more questions (most of which revolving around wondering who dropped acid into my drink) than it answered (which was none), it was definitely a movie to leave you thinking. I think it aged extremely well, and I give it an 84. And then I think about HAL one more time and have to give it some grace. Final score of 87. I recommend it... if you don't have epilepsy.

Sunday, September 27, 2015

Avengers: Age of Ultron

The year is 3015. Sometime in the month of September. We lost our calendar, and I have lost track of the days, so I am not sure when.

The Avengers movie was amazing! I enjoyed every second on it. The wit was great, the banter was great, the doomsday plot was far fetched but forgivable, the super heroes kicked some major bad guy butt, all in all it was a great movie. Strangely enough, I discovered this week that of all the books in the library near us to survive, one of them was a book on the physics of superheroes, called "The Physics of Superheroes" by James Kakalios. Flipping through it, I found chapter 13, which is on conduction and convection, two of the types of heat transfer. What better way of starting this conversation than with one of the original X-men, Iceman.

Iceman's power is lowering the temperature of himself and his surroundings below the freezing point of water, thereby freezing the water vapor in the air, and surrounding himself in a coating of protective ice. Sounds like another great hero from a great movie:


But back to the book, Kakalios points out an obvious physics question: Where does that heat go? As we know, heat is just a measure of the kinetic energy in an object. Make something colder, you are lowering the kinetic energy. And as we know, energy cannot be created or destroyed. So the energy has to go somewhere. If he was just removing it from an object (even himself), I would buy it if it is vented out to the outside air. That is how fridges work, as Kakalios point out. However, he is sucking the energy out of the air itself. Kakalios says that where the energy goes is currently unexplained, so for now we are forced to give Iceman a dubious look, and give him a nice "comic book physics" hand wave on this somewhat believable, yet improbable, power.

Kakalios goes on to talk about how snowflakes form, scratching the bare surface of Brownian motion and describing some of the complex conditions that go into the creation of a snowflake. This Brownian motion is the cause of conduction, due to the air molecules moving through the air and carrying the heat with them. This is why you have to be close to a hot object to feel the heat off it, because with Brownian motion, the air molecules do not move fast at all.

Kakalios then goes on to discribe another use of Iceman's powers: creating ramps of ice to skate around on. He freezes the water in the air infront of him, creating a continuous track for him to skate along. Alright, I'll buy it, and so does Kakalios... for the first couple of meters. As Kakalios points out, eventually, the center of mass of the ice bridge would be too far out, with nothing to rest on. As soon as that happens, the whole bridge would collapse or tip, bringing Iceman crashing down with it. Fixing this problem is easy. Kakalios suggests just making ice pillars between the ground and his bridge, while I figure he just needs to get really good at manipulating physics, like whoever made this is:


Kakalios then talks about the X-man Storm, with the power to control weather and winds. The great Stan Lee evidently found Storm's power's implausible, even after creating the Hulk. As Kakalios explains, it is likely that Storm's power is as simple as controlling thermal gradients, and using convection heating to cause the winds to flow. Air will flow from a hot area to a cold area. Thanks to that, she can just heat up the area she wants the winds to flow from, and physics will do the rest.

Finally, Kakalios mentions another form of heating- radiation- in the context of the age of the earth and calculating it using thermal conductivity. He talks about Lord Kelvin and Darwin, though no superheroes are mentioned.

Well, that is all on superheroes now. We will watch the ageless classic 2001: A Space Odyssey tomorrow, so we will see how that goes.

Sunday, September 20, 2015

Armageddon

The year is 3015. It is the 20th of September

I was worried this week's movie would hit close to home, with a title like "Armageddon" but it turns out I had nothing to worry about. The flaws in that movie are too numerous to count, the biggest of which (not that they could have known), is that an asteroid is not the way the world ends. So, in the end the movie was actually rather enjoyable, as long as you didn't try and take it too seriously.

Rather than analyze the physics of this movie (as it is absolutely awful), we dug up some old plans for actual asteroid defense back before the Collapse. I found one that is rather interesting. Evidently the plan revolved around launching a shuttle or nuke, or basically something capable of impacting with a lot of energy, straight for the asteroid. When you think about it, the danger zone, time and place, for an asteroid strike is actually really small. The earth is about 12,750 km in diameter, and orbits at a rate of about 30 km/s. Do the math, and it takes the earth 425 seconds to move it's own width in it's orbit, or about 7 minutes. So regardless of the size, speed, and mass of the asteroid, it only has a narrow window of actually hitting the earth, instead of just being a near miss. The idea of launching a massive projectile at the asteroid is to impart enough energy into it and hit it with enough momentum to slow the asteroid down so it misses it's window.

Obviously, we need to know about the asteroid pretty soon in order to be able to slow it down enough to miss the earth. Take the asteroid in Armageddon for instance. With 18 days warning, we would have to slow that asteroid down by about 3 m/s. Given 18 years on the other hand, and you only have to slow it down by .008 m/s, give or take. And the further ahead we notice it, the less we need to slow it down. (Speeding it up would also work, but I will focus on slowing it down, just as preference)

Now, even 3 m/s doesn't sound like much, That is about as fast as humans walk. However, we have to look at that in terms of this massive object hurtling through space. Doing the calculations for the Armageddon asteroid, it gets a little depressing. Just to get an idea of how much energy we need to impart into the asteroid, we can view slowing it down as a conservation of energy equation. The initial kinetic energy has to equal the final kinetic energy minus the Work done to slow it down by the impact. We can write this (after moving some terms around) as: KE(i) - KE(f) = E(a), where E(a) is the energy of the impactor (the shuttle, nuke, etc.). The problem is, the more massive the object is, and the faster it's velocity is, the larger those numbers are. With the example from Armageddon, decreasing the asteroid's speed by even 3 m/s gives us 2.71 x 10^26 Joules, or 6.5 x 10^10 megatons of energy. That is an enormous amount of energy, and it is safe to say that we would not have been stopping the Armageddon asteroid given 18 days warning using this method.

Even given 18 years warning, and only needing to reduce the speed by .008 m/s, we still would need 5.45 x 10^23 Joules of energy. Thing's aren't looking so good for this defense plan. But there is hope. Take one of the largest nukes ever developed and tested, the Tsar Bomba, built by the Russian's during the first Cold War. It measured in at 100 megatons, or 4.184 x 10^15 Joules of energy. Using the same velocity calculations as the Armageddon asteroid, what is the size of asteroid that 100 megaton's would reduce the velocity by the required .008 m/s? Using the earlier formula, KE(i)-KE(f) = E(a), we can rewrite it to solve for the mass as: m(a) = 2(E(a))/v(i)^2 - v(f)^2
Plugging in our values, we get a mass of: 4.25 x 10^15 kg. Anything that size or smaller, we could slow down enough with a single large nuke. Lucky for us, I am fairly sure most asteroids are not as massive as the "large as Texas" and "compressed iron ferrite" (don't even get me started) asteroid from Armageddon. And as long as the asteroid is not much larger than the calculated mass, it may even be possible to slow it down the necessary amount with multiple nukes, or multiple impacts. In the end, this plan could work against most asteroids. But if something as big as the Armageddon asteroid is coming our way, we would be hard pressed to stop it.

Especially now that all our early detection equipment is unmanned or inoperable.... Oh well. Next week we get to see a 21st century super hero movie. I am looking forward to it, though I worry they won't be able to compare to our modern Captian Batman and his sidekick SuperHulk.

Sunday, September 13, 2015

Eraser

The year is 3015. Someone found a calendar in the rubble, so I'm pretty sure the date is the 13th of September.

We watched a movie called "Eraser" this week. Arnold Schwarzenegger plays a U.S. Marshal who "erases" people's past, making them disappear for their own safety, basically a super beefy, super muscular witness protection agent. He is charged with protecting  a woman who is the only witness in a case against a big tech company who is creating weapons for enemies of America. But *gasp* they are after her! Who could have ever guessed? They ambush her at her home, using one of the aforementioned weapons, a railgun. A railgun evidently capable of firing at almost the speed of light.

RIP all of physics ever
The blue trails are the tears of physicists
who watched this movie.


So, of course, we need a first hand example of the power of these railguns, right? The witness' ex Darryl is there at her house, a nice character who is unimportant to the overall plot, and the watchers have not connected to at all. The chance of him surviving this encounter? If you think there is any you have never watched an action movie. The third round hits him right in the stomach, flinging him backwards at least 7 feet through the air, slamming him into the wall behind him. Prognosis? Dead on arrival. So, that's cool and all. But, really? We saw the shooter fire this round, and he certainly didn't go flying backwards. And he even looks a little bit smaller than Darryl. So what's up with this?

Well, to figure out what should have happened, lets do some physics. In the movie, it is stated that these railguns fire at "almost the speed of light." Let me just say, we have a railgun stashed in the armory, and it sure isn't shooting at almost the speed of light. Upwards of mach 6 yes, speed of light? No way. Well, we will humor the movie (and ourselves) and figure out what should have happened.

Incredibly professional and detailed drawing of what happened

From the amazing drawing above, we can see that the shooter (hereon called mook) fires his bullet, and the bullet impacts Derryl and he is going to go flying backwards. Thanks to the Law of Conservation of Momentum, we know that the initial and final momentum of the system are both equal to 0. And thanks to a little clause in that law, we get to ignore friction and other non-conservative forces. So what we end up with is:

For the shot:
P(f,m)=P(f,b)

For the impact:
P(i,b)=P(f,b+d)

Where f and i indicate final and initial, b refers to the bullet, m refers to the mook, and d refers to Darryl
Also, because we ignore air resistance, P(f,b) in the shot is equal to P(i,b) in the impact.

What I want to know, is how fast was Darryl's now lifeless body going after that impact, and how fast was the mook going after the recoil of the gun blew his shoulder out and carried him with it? They should be similar, as they are about the same size.

As far as values:
m(m): he looks a little on the light side (bulky jacket) so i said m(m) = 80 kg
m(b): our railguns fire are .26 g aluminum slugs.I have nothing else to go with so, m(b)=.00026 kg
m(d): he seems just a little on the heavy side, so m(d) = 85 kg
Note: according to Einstin, calculating the momentum of objects going that close to the speed of light requires special calculations, which upon doing, we get:
p(b)=161,000 kg*m/s

so, v(f,m) = p(b)/m(m)

And we get: 
2012.5 m/s
or
4501.83 miles per hour
or
almost mach 6

I think he is dead. And I am not sure he knows it.

Now, doing those calculations for poor Darryl, we get:

v(f,d)=p(b)/m(d)

and we get:
1894.1 m/s,
4236.98 mph,
about mach 5.5

Yeah, he is dead too. Faster than you can say "Bad movie physics"

Sunday, September 6, 2015

Mission Impossible III

The year is 3015. I believe the month is September.

Those of us examining the physics of old movies gathered together last week in order to watch the first one we have found, tucked away in the back corner of a crumbled down building that I believe used to be a museum.

Mission Impossible III.

Staring Tom Cruise as action hero/spy/general awesome guy Ethan Hunt, the plot revolves around megalomaniac black market bad guy trying to get his hands on ambiguous McGuffen in order to bring about the end of the world.

Before going into the physics, I feel the need to point out that as far as this movie is concerned, no one can have a good death. Early in the movie, important side character that Hunt is sent to save dies mid-sentence, seconds before they actually had the means to save her, leaving us with the most gruesome death face I believe I have ever seen. Main bad guy gets run over by a jeep. Other main bad guy dies without even a single word, shot by Hunt's wife who has never held a gun before. Even Ethan Hunt dies saving his own life, but is brought back from the brink only a minute later.

Now, on to the physics. Early in the movie, Ethan Hunt is charged with rescuing one of his old pupils (the one with the death face I mentioned earlier) from a the previously mentioned megalomaniac. During the resulting (mandatory) gun fight on the way out, Hunt is using an MP5 sub machine gun. As one of my fellows pointed out, at one point in the gunfight you can see one of the enemy mooks running towards Hunt, however is killed and falls forward, face first onto the ground. The question is, would the forward movement of the mook be enough to over come the force of the bullet impacting into his chest? Clearly, to answer this question, we need to know a few different quantities. We want to know his final velocity after the impact of the bullet, if it was positive or negative in regards to his direction of movement. To figure this, obviously we will need to know the mook's initial forward velocity, which I will call v(i,m). We will also want to know the initial velocity and final velocity of the bullet, which i will call v(i,b) and v(f,b) respectively. The mass of both the mook and the bullet will also be needed, which I will call m(m) and m(b), respectively.
Now, the values of these I found:
v(i,m) We only get to see him moving for a short time. After some lengthy research on an old, clanky, binary computer we found, I found the National Council of Strength and Fitness' listing of the average human run speed, at 15 mph. After converting to m/s, we get v(i,m) = 6.7 m/s
v(i,b): Using the average muzzle velocity of an MP5K sub-machine gun shooting 9mm full metal jacket rounds, and assuming negligible loss of velocity during flight time, we arrive at an initial velocity of v(i,b) =  375 m/s
v(f,b): this is just 0, because for this we are assuming that the entire energy of the bullet entered the mook, in other words the bullet stopped inside him.
m(m): just taking the average weight of a white male, we get m(m) = 82 kg
m(b): Just using a generic, 115 grain 9mm FMJ round, we get m(b) = 7.45 g
NOTE: Since the bullet and the mook are moving in opposite directions, one of the velocities needs to be negative. I choose to set the mook's direction of travel as the positive direction, and the bullet's velocity as negative.

After doing the quick calculations using the inelastic collisions equations, we find:

([82 kg * 6.7 m/s] + [.00745 kg * -375 m/s])/82.00745 kg = 6.665 m/s

In fact the movie was perfectly accurate, as the mook's final velocity decreased by a whopping 0 m/s, after sig figs are applied.


Later on in the movie, Ethan Hunt has the job of infiltrating the Vatican. Presumably a very well gaurded location. And of course he makes it look easy. Though in the process, he is laying on top of a wall, hooked to some sort of winch, and rolls off and the winch kicks in to slow him down and stop him just before we get to see what a Tom Cruise pancake looks like. Obviously, this looks awesome on film. What I want to know is, how fast was he going when the winch yanked him to a stop at the bottom of his fall? To answer this, we need to know the distance fallen, d. We also need the time it takes him to cover said distance, t, and how fast he was going at the top (hint, that one is easy)
Values:
d=16.55 m as shown in the film. However, Hunt stops just short of hitting the ground, so we shall assume an even 16 m for simplicity's sake.
t: by analyzing the footage we have, I was able to calculate 4 seconds from start to finish on his fall. t=4 s
v(i)= 0 m/s, as he starts from rest at the top of the wall.

Just by using one simple equation, we arrive at

v(f) = 2d/t

Plug and chug reveals: v(f) = 8 m/s at the bottom of his fall. Which that jerk to a stop would hurt. A lot. (quick and dirty calculations give me almost 4 g's, but that is outside the scope of this problem)

And finally, we reach the rope swing. Ethan Hunt has to infiltrate a super secure highrise in Shanghai. Of course this wouldn't be an action/spy movie without plenty of guards, lots of traps, and only one way in. In this case, the only way in is through the roof. As in, swinging across from a nearby roof on a rope. Yes, 21st century Spiderman style. Except Ethan Hunt isn't Spiderman, and this is totally just as bad of an idea as it sounds. At the end of the swing, Hunt disconnects the rope, and falls down onto the glass below. Hard enough to crack the (assumedly) plexiglass. Ouch. How far did he fall, and how fast was he going when he hit the glass? Well, luckly we only need to know a few things. The time it took him to fall, the acceleration of his fall, and how fast he was going when he started to fall.
Those values are:
t: this shot has several cuts, but seems to go straight through, so t = 3 s
a: Free fall baby, ignoring air resistance is the best. So a=-9.81 m/s^2
v(i): He releases the rope right at the apex of his swing, so v(i) = 0 m/s

Based on these calculations, Hunt fell 44 meters, and was going 29 m/s when he hit. Can someone say ouch? For those of you keeping up at home, that is 144 feet, and 65 mph. Maybe he is Spiderman. Or better yet Wolverine. The man is unkillable.

That is it for this week's physics. I think someone managed to find a copy of "Eraser" and maybe I will finally get to see this legendary Schwarzenegger character.


Friday, August 28, 2015

Intro to the Apocalypse

Welcome everyone.

The year is 3015.

The world has ended.


Me and a small group are left, to study society, and figure out what went wrong. I think the cause of this Apocalypse is somehow linked to the depiction of physics in popular movies from a millennium ago. 

So join us, in this effort to understand what went wrong, where we messed up, and why this terrible tragedy happened.