25
Sep 14

Action Physics, No. 2 – Super Strength

Among his seemingly endless list of superpowers, super strength is probably one of Superman’s most recognizable and most commonly used superpowers. It was the one that was shown on the very first issue of Action Comics.

http://s1.stliq.com/c/l/f/f0/30228236_un-utente-ebay-vender-all-asta-action-comics-0.jpg

We’ve seen things like this everywhere – Superman lifting cars, buildings, even planets with his bare hands. As an example, I’m going to use this image of Superman holding up a plane by its nose:

http://veryaware.com/wp-content/uploads/2013/06/SupermanReturns3.png

Unfortunately, it doesn’t matter how strong Superman is – this feat is simply impossible. A Boeing 747 commercial airliner has a maximum take-off weight of almost 1 million pounds. In other words, in order to do what we see in the image, Superman has to exert a force equal to 1 million pounds. However, there’s something we’re not accounting for here: pressure.

Pressure is simply the amount of force applied over a certain area. Superman is applying a tremendous amount of force over a tiny area – the size of his hands, or approximately 16 square inches. Therefore, the plane has to sustain a pressure of more than 60,000 pounds per square inch – far greater than the pressure caused by being hit by a bullet. Imagine trying to stop a falling orange with a knife sticking straight up. If Superman had the strength to withstand the weight of a 747, he would simply pierce through the plane as it continued to fall.

Likewise, this is true for virtually anything that Superman is commonly depicted as lifting. Cars would buckle and bend under the pressure. Buildings would crumble and fall apart as soon as Superman tried to lift them. How does he even maintain balance while holding these massive things over his head?

Superman’s incredible strength is often attributed to the increased gravity of his home planet, Krypton. This article attempts to calculate how much larger Krypton would have to be in order for Superman to be strong enough to exert the amount of force he does. It’s not optimistic: Krypton would have to be “3,000 times the mass of the sun.” It would be nearly impossible just to send a space ship into orbit from Krypton, much less all the way to Earth.

Even further, Superman may have been born on Krypton, but he grew up entirely on Earth. His bones and muscles should have developed for Earth’s gravity, not Krypton’s. In fact, astronauts lose muscle and bone mass incredibly quickly in space, to the point that they often have trouble walking upon returning to Earth. They have to run on a special treadmill pretty much every day just to prevent too much bone loss. Superman, on the other hand, just flies around everywhere. That can’t be good for exercise.

http://s.hswstatic.com/gif/exercise-in-space-3.jpg

 

So Superman’s super strength is pretty much impossible in every way. Nobody will ever be able to lift a million pound plane. But actually… we can. Not only that, but we can also send it at 600 miles per hour through the air. Scientists and engineers have developed machines that are capable of both flight and super strength, and they have changed our lives by allowing us to travel across the globe. Sure, we may not be able to pack it into as small a package as Superman, but I don’t think that even Superman can claim to transport millions of people around the world every day, year after year. A commercial jet is a real life ‘superhero’ with real-life ‘superpowers.’

http://i417.photobucket.com/albums/pp252/infamousgamma/superman-jet.jpg


18
Sep 14

Action Physics, No. 1 – Flight

To kick off this blog I will be taking a look at one of the oldest and most iconic superheroes – Superman! He also happens to be the one who probably breaks the most laws of physics, but let’s start small here. Today, we’re looking at Superman and flight.

The act of flying is something that eluded humanity for thousands of years. At its most basic, it can be described as “not falling” – in other words, counteracting the force of gravity. Take a look at this image of Superman flying:

http://cinematicjackass.files.wordpress.com/2010/09/s8.jpg

How exactly does he counteract the force of gravity? In order to fly, you must apply a force. Birds fly by pushing the air with their wings. Planes fly by pushing wings through the air, and using the wings to redirect air downwards. But Superman? He just stays still, holding a cool pose with his arms outstretched. He is doing absolutely nothing to oppose gravity. Logically, he should simply fall to the ground.

It is possible that Superman could simply exert a lot of force during takeoff, and then glide using the force of the initial push. After all, Superman was originally described as being able to “leap tall buildings with a single bound.” (For the record, flying was only added to Superman’s abilities after he first debuted, in order to make animating cartoons easier.)

Let’s assume that Superman can leap the tallest building when he debuted, the Empire State Building. How much force would that require? The Empire State Building is 1,454 feet tall at its tip. For my calculations, I will convert all units to metric. 1,454 feet is 443.2 meters. We can use the equation v^2 = 2gh to calculate the velocity that Superman would have to begin with in order to clear the building. Plugging in 443.2 m for h and 9.8 m/s for g (the acceleration of gravity of Earth), we find that Superman needs to achieve an initial velocity of 93.2 m/s, which is approximately 200 miles per hour. If we assume that Superman can achieve this speed in 1 second, and that he weighs 107 kg, then we can use Newton’s second law, F = ma, to find that the force required to leap the Empire State Building is 9,972 N.

http://i2.kym-cdn.com/photos/images/newsfeed/000/370/705/37c.gif

This figure is actually not that impressive. In fact, according to Wolfram Alpha, a weight lifter can achieve a maximum force of about 8000 N during a clean lift. Of course, we are not accounting for big factors such as air resistance, energy lost to the ground, or even how Superman would survive the impact of falling 1,454 feet to the ground. Still, with the right technology such as a jet turbine or a rocket, it’s not hard for humans to generate much greater thrust. After all, we have been able to leap to the moon in a single bound (actually, three rocket stages, but I digress).

However, there is still a problem with this. In most depictions of Superman, we are often treated to a scene where we see Superman flying or hovering, and then, out of sheer will, he accelerates himself even faster. For example:

http://media.giphy.com/media/Aon0ejxr6vdJu/giphy.gif

Sorry Superman, it doesn’t matter how strong Krypton’s gravity was, but you cannot accelerate without thrust. You cannot push off against nothing. (Also, why is his cape billowing? He’s IN SPACE.)

One more question. How high would Superman have to fly in order to be confused for a bird or a plane? When migrating, geese usually fly at an altitude of around 3,000 feet, which is about 1000 meters. Their wingspan is around 1.5 meters. Planes usually cruise around 12,000 m and have wingspans of around 60 m. If we simply take the ratio of wingspan to altitude, geese have a ratio of about 0.0015, and planes have a ratio of 0.005. On average, the arm span of a human is very similar to their height, so let’s assume Superman’s wingspan is 6’ 3”, or about 1.9 meters. Based on these figures, Superman would have to fly at an altitude of between 380 meters and 1270 meters to be confused for a bird or a plane. This would put him at between half and 1.5 times the height of the Burj Khalifa.

In the next part of this analysis, I will be taking a look at Superman’s strength. We’ll find that sheer strength is not enough for him to accomplish some of his deeds. Stay tuned!

I’m also looking for suggestions as to what I should cover next. Leave a comment and tell me what you’re interested in, and I may have some thoughts on it myself!


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