Sunday, September 27, 2015

Why can't The Flash run at the speed of light? - Because of Physics, that's why...

So, by now, we all understand that Albert Einstein was a genius, and everyone knows his most famous equation, E=mc2, but few seem to understand how this ties into his theories of Special and General Relativity. And there is a very good reason for this, its because his theories are complicated. So I, a freshman in a physics in film class, am going to do my best to explain special relativity.

Special Relativity is used for objects traveling on a constant velocity, whereas General Relativity is used for objects that are accelerating. The first thing needed to explain why the flash cannot run at the speed of light is to define the variables behind Einsteins infamous equation. Below are the variables.

          E = Kinetic energy for the object in motion
          m = Mass of the object
          C = Speed of light = Constant = 3x108 meters per second

Since C, the speed of light, is a constant, this means the the kinetic energy and mass of the object are the only fluctuating values. This means that the faster one moves in a single direction, will result in an apparent gaining of mass from stationary spectators. 

So, focusing on Special Relativity, our superhero, The Flash, comes into play. If he were to run by a stationary spectator, he would appear to be gaining mass as his speed increased. Once he nears the speed of light, his apparent mass has become so grand, that he is no longer able to produce enough force against the ground to accelerate any further, thus only being able to reach a final velocity close to the actual speed of light.

There are other factors that come into play with Special Relativity, such as the perceived slowing of time and the perceived length of object moving at such a speed. But, seeing as these play no real factor into the possibility of The Flash making it to the speed of light, I will save them for another date (arguably because my brain is still spinning from trying to understand the principles themselves).

This information is all thanks to chapter 6, titled "Like a Flash of Lightning - Special Relativity", in The Physics of Superheroes, by James Kakalios. In, which is supposed to be a "basic" understanding of physics, except for maybe this particular chapter.

Sunday, September 20, 2015

NASA's comet-ment to kicking your asteroid.

As we proved in class, Armageddon's way of deflecting incoming asteroids is completely useless and would just result in two halves of an asteroid hitting the sides of the planet instead of one giant asteroid. So in the real world, what is the plan to deflect or destroy an incoming asteroid?

Well before I get to NASA's actual plan, I first want to describe an upcoming project NASA is planning that will hopefully lead to a better understanding of asteroids and their place in our solar system. The project is called ARM or Asteroid Redirect Mission. Its purpose is to locate a small asteroid close enough to Earth and to redirect it so that it will safely orbit our moon. this will then let NASA astronauts go on a mission to analyze many factors behind the asteroid such as its chemical composition and topographical features. This will further our understanding of asteroids in our solar system and how to deal with them.

With that being said, NASA was called upon by Congress in 2005 to present defense plans against an incoming asteroid. After two years of research (because of such a reduced budget), they returned to present their plans to Congress. They presented four plans that worked best for different asteroids, but argued that the most reasonable and most effective plan is to detonate a series of "standoff" nuclear blasts. This means that nuclear bombs would be sent near the surface of the asteroid and detonate close enough to push the asteroid off course little by little. NASA scientists agreed that having the bomb on the surface or beneath the surface would create smaller chunks of asteroid with unpredictable trajectories. Having a series of nuclear bombs detonate near the asteroid would push the asteroid into a different trajectory with every blast. Below, I have drawn a diagram of what this would look like. the dotted line would be the original course of the asteroid, the small asterisks would be nuclear explosions near the asteroid, and the solid line would be the resultant course of the asteroid after the detonations.


Through the series of nuclear detonations, The course of the asteroid would slowly be altered. After enough explosions, the course would change enough to miss the Earth entirely. By having the nuclear bomb detonate near the asteroid, and not on the surface, you lessen the risk of pieces of the asteroid breaking off and entering the Earth's atmosphere.

All we can hope for is that NASA uses astrophysicists and make them learn about nuclear explosions, and not use nuclear technicians and make them learn astrophysics, or better yet... have both of them work together to save the planet...

Sunday, September 13, 2015

Can I Erase This Movie From My Memory?

Where to begin with the movie Eraser? There are so many bad examples of physics, but I only have so many words I can type...

So let’s begin with analyzing why dual-wielding 2 railguns would effectively kill you (unless you’re Arnold Schwarzenegger of course).

In the movie, after being fired upon for what seems like ages, Arnold's character picks up 2 railguns and decides to give the enemy a taste of their own medicine. He then goes on a firing spree, spraying bullets at near the speed of light at his enemies. Since the bullet is traveling near the speed of light, I approximated 95% of the value for the speed of light which resulted in 2.85x108 m/s. Since I am going to examine the physics of the momentum from the guns, I will be using the conservation of momentum equation below.

mavaf + mbvbf = mavai + mbvbi

Here are the variables:
           
            ma = Mass of Arnold = 115 kg
            mb = Mass of bullet = 0.100 kg
            vai = Arnold’s initial velocity = 0 m/s
            vbi = Bullet’s initial velocity = 0 m/s
            vbf = Bullet’s final velocity = 2.85x108 m/s
            vaf = Arnold’s final velocity = ?

Cancelling all the variables that equal zero gives us this equation which we then solve for vaf.

Vaf = -mbvbf
           ma

vaf = -(0.1)(2.85x108)
        115

Vaf = -248000 m/s

This means that after firing the railgun, Arnold would have been sent back at a speed of 248,000 meters per second. But this is for only 1 railgun. In the scene, Arnold is dual wielding a pair of railguns. This effectively doubles the speed at which he would be sent back, meaning that had he fired both railguns at the exact same time, he would have been sent back at 496,000 meters per second. But as we all know, with muscles like his, Arnold would have resisted all that force and most likely have pushed the guns forward while firing them...

Now, to examine how fast the villain would have flown back had Arnold hit him with a bullet fired from a railgun. We will be using the same equation as before with the same variables except for the variables dealing with Arnold, we will switch them out with variables relating the villain like, as we see below.

            mv = Mass of villain = 90 kg
            vvi = villain’s initial velocity = 0 m/s
            vvf = Villain’s final velocity = ?

We also need to assume the bullet stays with the villain, so the final velocity of both the bullet and the villain will be the same. This gives us the resulting equation for us to solve for vf.

vf = mbvbi
         mv+mb

vf = (0.1)(2.85x108)
       (90) + (0.1)

vf = 316000 m/s



This means that the villain, after being shot with a railgun, would fly back at a speed of 316,000 meters per second, and since he is not the main character, he can actually die in the movie. Even though we haven’t talked about force in class yet, I believe being shot with a bullet fired at that speed and having you fly back at that speed would have a high enough force to kill you, so long as you’re not Arnold Schwarzenegger.

Sunday, September 6, 2015

Impossible Physics, The Movie

~~~~~~~~~~~~~~~~~~~~~~~~~Question 1~~~~~~~~~~~~~~~~~~~~~~~~~

How long of a rope would Agent Hunt need to swing from an adjacent building to the building where the Rabbits Foot is being held?

Towards the end of the movie, Agent Hunt must swing from an adjacent, taller building, to the building across the street in order to infiltrate through the roof. Luckily for anyone who wants to know the possibility of this, the measurements of the buildings and the distance separating them are given to us in the previous scene. The list of measurements needed to find the length of rope needed are below:

                  Difference in height of the two buildings = Building height #1 - Building height #2
                                                                                    =    226 meters   -   162 meters
                                                                                    =                 54 meters
                  Distance between the two building = 47.55 meters

If we use the Pythagorean theorem, we will be able to calculate the angular length of rope needed to cover from the top corner of Building 1, to the top corner of building 2. Below is a figure explaining the situation.

So to solve the equation:        h2   +   d2   =   l
                                                   
                                                     (54)2   +   (47.55)2   =   l2
                                                           
                                                             l2   =    5177 meters
                                               
                                                  l   =   72 meters

So, for Agent Hunt to be able to swing from the corner of the first building to the corner of the second building, his rope would need to be just over 72 meters long (to accommodate for his height).

~~~~~~~~~~~~~~~~~~~~~~~~~Question 2~~~~~~~~~~~~~~~~~~~~~~~~~

How much heat would it have taken to melt the side of the armored truck?

During a chase scene, thermite is used as chemical reaction to melt the side of the armored truck, so that the squad can steal the rabbits foot inside the vehicle. The list of measurements needed for this question are below:

               Heat capacity of the metal of the truck = C
               Change in temperature = ΔT
               Mass of sample = m
               Amount of heat transferred = q

So, after a few brief internet searches, I found that the metal used for the armored truck is tempered steel. Tempered steel has a heat capacity of .490 kilo-joules per kilogram per kelvin. The change in temperature is the temperature of the ignited thermite (2500 degrees Celsius or 2773 Kelvin) - the temperature of the air that day (295 Kelvin on a normal day). The mass of a 1 in x 1 in x 1 in piece of steel weighs .283 lbs or 128 grams. For this question, the size of the piece of steel melted is assumed to be 24 in x 24 in x 1 in.

               C = .490 kJ/kg/K
               ΔT = (2773-295) = 2478 Kelvin
               m = (128 grams)(24)(24) = 73700 grams or 73.7 kilograms
               q = ?

So, to solve the equation:        q=mCΔT                                                         

                                                                 q = (73.7kg)(.490kJ/kg/K)(2478K)

                                                 q = 89500 kJ

So for the thermite to have actually melted the side of the armored truck, it would have had to have created 89500 kilo-Joules of heat energy. This does not seem likely...

~~~~~~~~~~~~~~~~~~~~~~~~~Question 3~~~~~~~~~~~~~~~~~~~~~~~~~

How fast would Agent Hunt had to have run to make it to his wife in the given amount of time during the final chase scene?

After calling the evil guy and getting the address of his wife, Agent Hunt sprints towards the location to save her. He is being directed by his tech savvy friend on the other end of a phone. He runs there super quickly. The needed measurements are as follows:

              Distance ran = d
              Time spent running = t
              Average speed = v

After re-watching the scene. The distances given to Agent hunt by his tech friend add up to 2220 meters. This added to an additional 100 meters for unspecified running reaches 2300 meters ran by Agent Hunt. After timing the scene, it was determined that Agent Hunt ran this far in 68 secs.

               d = 2300 meters
               t = 68 seconds
               v = ?

So, to solve the equation:         v = d/t
                                                 
                                                 v = (2300 m) / (68 sec)
             
                                                                v = 34 meters/sec

So, in conclusion, for Agent Hunt to have been able to run that far, that fast, he would have to have been running at 34 meters per second. I think Tom cruise should quit acting and compete with Usain Bolt in the next Olympics.