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How Much Kinetic Energy Could Black Panther Collect From Bullets?

A new clip from the upcoming movie Black Panther was recently shown during an episode of Ellen. In the scene (which I assume isn't a spoiler, since it was on TV), the Black Panther is in pursuit of (or being pursued by) some people in another car. As the Black Panther rides on top of the car (which is, of course, the most efficient way to travel as a superhero), the bad guys are pelting him with bullets. Honestly, I shouldn't make such judgements—maybe they're not bad, just misunderstood.

Anyway. As the Black Panther is getting hit by bullets, the driver of his car says:

"hey look at the suit! You've been taking bullets—charging it up with kinetic energy"

After "charging up" the suit, the Black Panther uses some type of energy burst to flip over a car. OK, that is the scene that I'm going to look at.

What is kinetic energy?

The first obvious thing to discuss is the definition of kinetic energy. In short, it is a type of energy—but what is energy? It turns out that in a system with no external interactions we can calculate this thing called energy. The cool part is that this calculated value of energy doesn't change for this closed system. We call this the work-energy principle and it's super useful in physics (and other fields too). If you want a slightly more in-depth explanation of energy, here is an older post that might help.

When dealing with energy, it helps to be able to calculate the energy in different forms. One type of energy is the energy an object in motion would have—we call this kinetic energy. The kinetic energy depends on both the mass and the velocity of the object. Here is the mathematical expression for kinetic energy.

What happens to the kinetic energy of an object (like a bullet) when it collides with something (like Black Panther's super suit)? If the bullet slows down, then its kinetic energy must decrease. In a closed system, the total energy is constant such that this decrease in kinetic energy must be accompanied by an increase in some other type of energy (like thermal energy).

How much energy from bullets?

In the case the Black Panther scene, it appears that the impact of the bullets lead to an increase in some type of stored energy in his suit (maybe like in a battery or something). But how much energy could he get from these bullets? To estimate this, I need three things: mass of bullet, speed of bullet, and number of bullets.

Let me just assume that the bad person is using an assault rifle like the M16 (I can't tell exactly what weapon is being used). [According to Wikipedia])(https://en.wikipedia.org/wiki/M16_rifle), the M16 uses the 5.56x45mm NATO round (mass of about 4 grams) with a muzzle speed of 960 m/s. With this, I can calculate the kinetic energy of one bullet.

That's almost 2000 Joules. If you move a textbook from the floor to a table, that takes about 10 Joules of energy. So a bullet has significantly more energy—but is it enough to be useful? If I had to estimate (and apparently I do), I would guess about 20 bullets hit Black Panther, so that would be on the order of 40,000 Joules of kinetic energy from the bullets. For now, I'm just going to assume all of this kinetic energy gets converted into the energy in the suit (it's super advanced so it can do that).

OK, is this amount of energy enough? It depends on what you want to do. If you want to use it to pick up textbooks, you are all set (and more). But what if you want to charge your smartphone? An iPhone battery has about 20,000 Joules of energy stored in it. So, yes the Black Panther could use the kinetic energy from those bullets to charge two iPhones.

How much energy to flip a car?

Everyone knows that the Black Panther isn't going to use the kinetic energy charge his phone. That would be silly. No, he is going to make some type of force field that flips that car over. It's going to be awesome.

But how much energy would that take? Let me make some assumptions. First, I am going assume that the car moves up a distance of 3 meters and that all of this is done by the Black Panther energy thing. Second, I need to estimate the mass of the car. I'm going with 2,000 kg. That's it, now for the physics.

If I want to lift something up off the ground (like a textbook or a car), I can calculate another kind of energy—gravitational potential energy. Then if you lift something of mass m a height h, the change in gravitational potential energy would be:

In this expression g is the gravitational field and has a value of 9.8 N/kg on the surface of the Earth. Using a height of 3 meters and with the mass of the car, this would take 58,800 Joules. OK—that's not too far off from my estimate. Really, just a few more bullets or some other stored energy to add to this and boom—you just flipped a car.

I'll be honest, I didn't think this would work.

Read more: https://www.wired.com/story/how-much-kinetic-energy-could-black-panther-collect-from-bullets/

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