Last week I made a blog post about how muzzle brakes on a firearm help reduce vertical recoil by venting the pressurized gas horizontally outside the barrel. But that still leaves the question as why vertical recoil still occurs. Obviously it isn't perfect, but human error can't be the only factor to why firing a gun lifts the barrel upwards.
Funnily enough, we've actually talked about this in class. It's just a simple torque diagram.
Firearms are designed with the grip of the gun placed below the barrel. Because of this, whenever the gun is fired, the force pushing the firearm back along the length of the barrel causes the entire system to rotate.
PSA: Don't put your finger in the trigger guard unless you intend to fire
Some companies have improved this by raising the grip very close to the barrel, which does help to reduce recoil, but they can only get it so close. Theoretically, if you were to hold a gun with your hand directly behind the barrel, then vertical recoil would not be much of an issue... But aiming would. Notice how Iron Man doesn't have to worry about vertical recoil.
Placing the stock of a firearm against your shoulder does help prevent vertical recoil, but, once again, it isn't perfect. Typically, weapons with stocks on them also fire more powerful rounds, meaning that the force is larger, which also means that the torque is larger, making vertical recoil even larger.
A muzzle brake is a firearm attachment that extends the barrel of the gun. Below is a picture of a muzzle brake.
The point of a muzzle brake is to help increase accuracy by reducing vertical recoil when fired. It does this by venting out the gas horizontally in the muzzle brake, rather than letting it spread out in all directions as the bullet exits the barrel. When fired, a large amount of pressurized gas is created within the barrel, and immediately tries to escape, launching a bullet one way, and the gun back. When the gas reaches the muzzle brake, it has its first chance to fully escape and spread out, so it vents out the horizontally-aligned holes, creating a leftward and rightward force, rather than vertical forces.
So if this pressurized gas is shooting out the sides of this muzzle brake, it must be more concentrated. And if it's more concentrated, it must be more powerful. But what else could make it more powerful?
Surely, more pressure would make it more powerful...
Below is a list of different common rifle calibers. A small rifle, such as an AR-15 (Yes, in this case, an AR-15 is small) would have quite a bit of power coming out of the muzzle brake, but a heavier, quicker bullet shot out of a rifle chambered in .308 (7.62x51mm) would surely have more power. Even more so, a .50 BMG would have an immense amount of power. Below you'll see
Let's start with a peek at a muzzle brake on the end of a .308 rifle. (On the first clip, he cut a hole through the lettuce, so the bullet isn't actually hitting it. Probably.)
PSA: CLEAN YOUR FIREARMS AFTER USE.
Now let's take a look at a .50 BMG. Prepare yourself.
So yes, a muzzle brake will break stuff, quite spectacularly. But if you want to break stuff with a muzzle brake, it will cover you gun, not so spectacularly. Still, an interesting thought, especially when you consider that many tanks or artillery (or artillery tanks) have giant muzzle brakes on them. Maybe they could flip a car.
NASA wanted their space shuttle program to be completely reusable. Sadly, due to budget cuts, only the actual shuttle was reusable, and the boosters were ditched. On the other hand, Space X wanted to save as much money and as many resources as they could.
On the right is a picture of Space X's Falcon Heavy rocket, designed to, as the name suggests, lift a large payload into space, and on the plus side, at a much cheaper cost than before. On the left is a clip of the two "small" side boosters landing simultaneously after the Falcon Heavy's test flight yesterday. Sadly, the main booster missed the landing barge in the ocean and was lost.
By saving the boosters, we can save a lot of money and time that would be spent into making new ones for every launch.
Also, if you didn't know, the Falcon Heavy was carrying Elon Musk's personal car, a Tesla Roadster. They put a dummy in a space suit in the driver's seat, put "Don't Panic" on the display, and the radio, even though you can't hear it, is playing "Space Oddity." Or "Rocket Man." I don't remember.
If you want to check out more, here's the link to SpaceX's livestream, which also has the videos of the test flight, and a simulation of the test flight which are pretty cool.
On the left is Gav. On the right is Dan. They are the Slow Mo Guys.
As you can probably tell, they make YouTube videos of stuff in really slow motion, and are probably my favorite YouTube channel to watch. Not only is some of the stuff that they do really cool, but they're also quite entertaining. They're both British, and in the past few months, have sadly not been releasing that much content. But very recently, they revealed that they had teamed up with YouTube, and were given a much more "professional" show, so they're going to be releasing a lot more content, much quicker than they used to.
They are also a part of Rooster Teeth, an entertainment company which uploads YouTube videos daily. Fair warning - they are NOT school-friendly. Anyways, here are some of the stuff that they've done.
And there's plenty more where that came from.
Seriously, check them out, and subscribe. I really love their content.
Let's say that you're at IHOP, and you ordered a nice pancake. Or, if you're one of them, then you ordered a waffle. Despicable.
Anyways, when your delicious meal arrives, you reach over for the syrup container, and spread it over your meal. Every time, the syrup will spill out, and slowly spread out, as shown below.
Most simpletons would describe the liquid as "thick." A less "thick" liquid, such as water, would rapidly spread, ruining your meal.
This property is called, as you can probably guess from the title, viscosity. It is the measure of a fluid's resistance to gradual deformation under stress. High-viscous fluids include honey, syrup, mustard, and ketchup, and low-viscous fluids include water, alcohol, and milk.
The fluid on the left has low viscosity, such as water. The fluid on the right has high viscosity, such as honey.
It's debated that amorphous solids, including glass and many polymers, aren't actually solids, and are actually liquids with very high viscosity.
And ideal fluid, or inviscid fluid is a fluid that has 0 viscosity, and is only observed at very low temperatures in superfluids. This means that it flows without loss in kinetic energy.
Look at this picture, because there is something horribly, horribly wrong with it.
See it yet?
It isn't the fact that there's a child shooting, and it isn't the fact that she's shooting in a backyard.
It's the fact that she's shooting at targets on a fence, with nothing to stop the bullet behind it. There's a house there: Glass could break, and people could get injured. Maybe their television or their car will be destroyed.
This picture comes from a tweet of somebody teaching their daughter how to shoot.
The worst part about it is that he even says "teach 'em right" which he clearly isn't doing in the slightest. Also, he says that he's letting her shoot it for the first time. For somebody that young, they probably aren't prepared to deal with the recoil. If she fell back, there's no telling where she might shoot next if she accidentally pulls the trigger again. But there's a really easy way to prevent this: Place your hand behind her shoulder to prevent her from falling, and better yet, let her kneel for her first few shots rather than stand. It might not be the manliest way to shoot, but it's how I started.
For shame, amgonder20... For shame...
Sadly, the world is filled with people like this, and lots of people are injured every day. What's even more sad, is that people start to blame the guns rather than the users.
Now don't you start thinking that I am pro-guns and that I think every household should have firearms, because I don't. I am pro-intelligence. Guns SHOULD be regulated because of idiots like this, but I don't think that they should be banned.
Back to my point, there's so many easy ways to safely go target shooting. For starters, you could go to a shooting range. Crazy, right? It's probably the safest option, since there are plenty of other experienced people there that will help out and prevent others from doing something stupid. But if you don't want to do that, you could always alter your setup. When I go target shooting, I usually go to my uncle's house. He owns a few acres of land near Dansville. His setup is really simple: We go in his backyard, and set up some folding tables on flat ground. We keep every firearm unloaded unless it's about to be fired. Then, we fire towards a hill he has in his backyard, that way stray bullets always end up in the dirt behind our targets, rather than traveling into populated areas. When we finish, we pick up all of the spent casings on the ground, and do some more packing and cleanup. We use common sense, and only point firearms downrange. Nobody gets hurt.
I cannot stress this enough, so I'm going to bold it, underline it, italicize it, enlarge it, and give it it's own line of text.
IF YOU'RE EVER GOING TO BE NEAR A GUN, BE SAFE, AND USE COMMON SENSE. YOU AREN'T THE ONLY ONE IN DANGER.
If you look real close, you can see that the shotgun won't function anymore. This is what the muzzle looks like after the shot.
Now, if you don't know firearms, that isn't good. At all. And that isn't even mentioning the sharp metal bent backwards, which could stab you in the head if you tried to fire this.
THIS is why you don't obstruct a firearm when firing. THIS is just one reason why you clean your gun often. Obstructions can significantly alter aim, or completely destroy a firearm and mutilate its user.
If you're going to buy or shoot a firearm, just know what you're doing. Most of gun control is just common sense. You might think that gun enthusiasts are stereotypical hillbillies with no common sense, laughing as they wave their gun everywhere. But most gun enthusiasts simply enjoy the sport, and will forcefully stop you if you try anything stupid, because if just 1 person with a gun is an idiot, everyone around them is in danger.
There is one massive issue that I've noticed with this demonstration: that car wouldn't be able to tow anything. If it was an truck, van, or even SUV... It'd depend on the size of the trailer.
Anyways, this could be the difference between life and death, especially when you add in malfunctioning parts, bumpy roads, high winds, ice, larger turn radii, and the leading factor of road accidents: bad drivers (I would know, I'm one of them).
Whenever you move, there are reasons that you put all of the big stuff in the back (The "back" being the end that hitches to the car/truck) of a U-Haul. One is just to get it out of the way, to make it easier to organize later on. Another is because it's easier to transport, so it prevents accidents. And the absolute last thing everybody wants, especially when moving, is to get in an accident. Another way to get the weight distribution right, is to drive a bigger car. That's one reason why people tow with a pickup truck more than they tow with an SUV.
Cats have evolved to be the ultimate being. They have evolved to disprove somebody when they say "Nothing living can do that." Surely you've heard that "cats have 9 lives." Let's take a quick look at the cat.
As you can see, this is a cat. Fluffy, adorable, evil little thing. It looks harmless. It looks "cute." You wouldn't want to harm it, and you think it wouldn't harm you. But that's where you're wrong. Those paws have hidden claws in them, and whenever the cat wants, it can take them out and demolish their prey.
Cats are also usually really quick. Some can run almost 30 mph. That's quicker than Usain Bolt, who's record was almost 28 mph.
Cats can also climb almost anything, whether digging in with their claws, or jumping with insane strength and accuracy. They can jump from wall to wall, over and over. And if they're going fast enough, they can easily run along a wall and jump off, landing exactly where they wanted to. These things would put Spiderman to shame. And on the unlikely chance that a cat ends up in free-fall, it has a pretty damn good chance of surviving, due to it having a relatively slow terminal velocity, and some other factors. I'm pretty sure somebody else did a blog post about that.
Now let's scale up a bit, to something that would beat us in a fight, like a jaguar.
Quick note: If you're googling about jaguars, add "animal" after it, otherwise you'll get results from the car company, and end up with top speeds of over 100 mph.
Like house cats, jaguars have retractable claws, but a top speed closer to 50 mph. Much scarier. They prey on animals that I would only be fine with seeing in the wild through a scope, and usually win fights rather quickly. Chances are, if one had its eyes on you, you'd be dead before you knew what was happening. They're ridiculously fast, ridiculously stealthy, and ridiculously strong, like their domestic counterpart, just much bigger.
Other larger, scarier versions of cats include cheetahs, tigers, lions, leopards, and cheetahs. All fascinating animals that we would love to see, from the other side of a tall, electric fence.
"Everybody your entire life has been lying to you: Your parents, your friends, your teachers, and your coworkers.
It's time to know the truth: The Earth is actually flat. It has been this whole time, and the government has been lying to you.
So why has nobody fallen off of the edge? Well the edge of the Earth is very cold, so all of the water is frozen. We call this Antarctica, and it's so cold that modern technology doesn't work there, so we can't explore it.
Every single picture and video of the Earth taken from space is fabricated because the government wants you to think that it's round. Even NASA's 24/7 livestream from the International Space Station is fake.
Finally, a long time ago, people thought that ships were sailing off the edge of the Earth when they went too far away. But when technology improved and they stopped sinking, the ships came back, so people thought that the Earth was round because they were just going over the horizon. But in reality, if you zoom in really far, you can still see the ship, they're just really far away."
That wasn't an actual quote, but just some random crap I've heard from Flat-Earthers. Theories like this can be quite entertaining, even though at the same time, they kill my faith in humanity and give me brain cancer, kind of like the whole Tide Pod thing that was going on. Maybe society's messed up, or maybe I'm just a horrible person, but honestly, chances are, it's both.
I'm not even going to debunk flat-earth theories because you're on a physics website, so if you believe any of them, you shouldn't be here anyways.
Who doesn't like magnets and shooting things? Thankfully, a Gauss Rifle includes both!
This is a simple demonstration of a Gauss Rifle - it's safe, and provides a great visual of what's happening.
Quick disclaimer: I'm not what most people call a "smart" person, so chances are I don't actually understand what's happening, but I'll explain it best I can (I think it's simple enough that I shouldn't screw it up too badly, though).
The setup includes multiple magnets fixed in place, each with two non-fixed ball bearings as shown above. A trigger ball bearing is rolled toward the magnet, and accelerates as it gets closer to the magnet, until it collides. When it collides, it's momentum is transferred through the magnet and to the ball bearings on the opposite side. The second ball bearing on that side then gets the momentum, similar to a newton's cradle. It then disconnects from the magnet, since the force is strong enough to disconnect it from the magnet system due to it being farther away or something (That's what they said in the video). It then rolls at a higher velocity toward the next magnet, and this continues on to the end, where the final ball bearing gets launched into your younger sibling.
As you can tell, it works. I do have some questions on why, but I'm just going to hold off on further research with the hopes that we learn about it later in class.
That was a simple demonstration, however. What if we want something that makes a bigger hole? If you recall from last year, current through a wire generates a magnetic field. If a current was going through a wire directed into your screen, then the magnetic field would be directed clockwise around it. Now if this wire were facing left, and wrapped upwards and back leftwards in a loop, the magnetic field would direct into your screen.
Do that a bunch, and you get an electromagnet. So let's use that to accelerate our projectile rather than wimpy little magnets and the transfer of momentum.
Behold, the coilgun.
This animation shows a coilgun in action (When a coil is green, current is going through it). It's the same as the ball bearing experiment: a metal projectile accelerates from a magnetic field, and approaches another magnetic field, where it continues to accelerate until it leaves the barrel of the gun.
While doing research, I found a guy on YouTube that made a couple home-made coilguns. If you want, check it out.
Last week, I went on vacation Monday-Thursday, and missed school. Friday, I had no idea what was going on, partly because of my usual lack of sleep, and partly because I was missing most of a very busy week of classes.
Why was that week so important you ask?
It was the week before midterms, where the classes which only last 1 semester have a sudden rush of work before they end, and it was the end of the quarter, where you suddenly realize you didn't hand in that essay that you should've, because your teacher didn't it grade when they should've, so they did it right at the end of the quarter and put it in the gradebook late, so you didn't realize that your grade dropped 15 points. This was that lovely week of reviewing everything in every class right before a massive test, all while catching up on that work you completely "forgot" to do.
Back to my original point: I missed most of that week.
Surprisingly, I've done fairly well on my midterms so far, even Physics (to my surprise), but that's because I already had most of my review material and (sort of) knew what I was doing.
Sadly, I've screwed up in that part where you hand in work at the last minute, and my English grade isn't doing too well. Physics and Economics could be better too.
So long story short, don't take vacations when you're really busy, because it can only make things worse. Also, don't try to do schoolwork on a plane. People will bother you, the noise makes it impossible to think, and the wifi is so bad that you can barely load a webpage. And if that webpage is webassign, then it simply won't work at all.
Finally, one last lesson, don't expect it to be warm down South during a giant winter storm sweeping across the country, because even if you're in Houston, it can get below freezing. When I was down there, I checked the weather in Houston vs the weather in Rochester, and they were the same: 20oF. The entire city shut down because they weren't prepared to deal with the ice.
Guns have vastly improved since their invention, but typically still use a chemical reaction to produce a rapidly expanding gas that shoot a projectile wherever it's pointed. What's the issue with this? Currently, nothing. They're still some of the best weapons in our arsenal. But in the near future, there could be better alternatives: railguns.
A railgun is, as it's called, a gun. The main difference with it is that the force it uses to fire projectiles comes entirely from electricity rather than a chemical such as gunpowder. How does it work, you ask? Simple: Electromagnets.
A railgun consists of 2 parallel rails that connect to opposite ends of a power supply, so one is positive and the other is negative. When a projectile is inserted, it completes the circuit, which generates a magnetic field. When using a large enough power supply, this magnetic field can easily launch projectiles to incredibly high velocities. A turret mounted on the top of some tanks can fire a projectile at over 1.5 km/s, while a railgun could fire a projectile at over 2.5 km/s, giving it a much farther range and a much quicker travel time.
What other advantages do railguns have? Since ammunition in a railgun doesn't require any chemicals to propel it, the manufacturing could be much easier, and ammunition for a railgun could be much smaller than a normal bullet. They'd also be safer to transport because of the lack of explosives and easier to transport due to their reduced weight and size.
Am I trying to convince you that railguns are superior in every way? No. I haven't done too much research, I just think that they're really freaking cool. Especially since the US Navy currently has an experimental railgun prototype.
There's just something about explosions that make me happy.
Now if you watched the video, you'd notice that the ammunition in the railgun were definitely NOT small. That's because this is a US Navy prototype. This is designed to be shot at big, tough objects, such as a building or a battleship. And from the looks of it, the railgun would win.
A handheld prototype would definitely be much less powerful, and would probably require many technological advancements before they're practical enough to replace modern firearms. Still, they're pretty cool.
Making my last blog post left me bewildered about the wonders of time dilation, so I decided to Google it and make another post.
Apparently there's different kinds of time dilation: velocity time dilation, the one I mentioned in my previous post, has to do with the difference in the perception of time relative to something else. The other kind of time dilation is gravitational time dilation, which I'll get into later.
Velocity time dilation suggests that objects moving faster in relation to another object moves slower through time. As an object approaches the speed of light, the rate of time approaches zero. This suggests that a massless particle moving at the speed of light is completely unaffected by the passage of time. This form of time dilation supports a theory of forward time travel, where we can, as the title suggest, travel forward through time. This could theoretically be done if people were in a spacecraft moving at incredibly high speeds. 1 year of travel time for them could be over a decade of time here on Earth. In practice so far, it is calculated that people on the ISS (International Space Station) for 6 months aged about 0.005 seconds less than they would have here on Earth. 5 milliseconds is a start, right?
On the other hand, gravitational time dilation suggests that an observer under the influence of a strong gravitational field moves slower through time than those under the influence of a weaker gravitational field. This supports another method of forward time travel, which is why in the movie Interstellar, the crew had to spend extra fuel to land on a planet quickly and take off again during a survey mission. They were trying to save time because they were close to a giant black hole. In the movie, 1 hour spent on the planet was the equivalent to about 7 years on Earth if I remember correctly.
Remember to take all of this with a grain of salt, because I clearly don't know what I'm talking about. I actually skipped over all of the calculus sections of my sources in order to prevent my brain from throbbing any more than it already is.
I spent a decent amount of time browsing the internet for an answer on why we can't travel the speed of light, and have found many different answers contradicting each other. I'll try my best to explain them.
The first explanation I saw began with a reminder of equations: How force is proportional mass. In order to travel faster, you must accelerate an object in order to obtain a higher velocity. The main issue begins when the video I was watching started to explain that the faster you move, the more mass you have. This naturally went right over my head, but continued to explain how since the mass increases, the amount of force required to accelerate an object also increases. When scaled to nearing the speed of light, the amount of force required grows exponentially, essentially becoming infinite. This is just like an old problem: Somebody is standing a set distance from a wall, and moves toward the wall. Every time he moves, however, he can only move half of the distance to the wall. He will never reach the wall, but will get infinitely close to it, just like how an object can never reach the speed of light, but can get infinitely close to it.
The second explanation I saw was a roller coaster. I started to watch a video that began with somebody explaining some simple physics while in front of a chalkboard. Then, out of nowhere, they disappeared, and started displaying calming pictures with a new narrator with a soothing voice. It seemed strange at first, but I kept listening until I realized what they were trying to do: They tried to convince me that the reason we can never obtain the speed of light is because we're in a simulation. Naturally, I stopped to watch a different video.
The third explanation I saw was one I had never seen before, but was still interesting. They started by reminding us of simple 2-Dimensional motion. There's an x-axis, and a y-axis. If an object is moving along the x-axis, it is moving its entire velocity along the x-axis with no velocity along the y-axis, and vice versa. If that object is moving diagonal, however, it has a component on both the x-axis, and the y-axis. Then, he brought Relativity into play. He explained that in reality, every object in the universe is moving at the speed of light, just not along our traditional axis. He put space along the x-axis, and time along the y-axis, saying that we travel the speed of light through spacetime. If we're traveling vertically in this instance, then we travel through time at the speed of light, but not through space. In our eyes, we would be at rest. On the other hand, if we are traveling diagonally, we are traveling through both space and time, but both components at a slower rate than the speed of light. So if travelling through time at the speed of light is how we usually perceive time, then that means that the faster we travel, the slower we travel through time. This especially interests me because of an experiment where three atomic clocks were synchronized. One was kept stationary on the Earth's surface, and the other were flown around the Earth in planes in different directions. After two full revolutions around the Earth, the clocks were no longer synchronized, and supported relativity. Another thing that interests me with this theory is that it actually seems plausible to travel the speed of light through space, but it would have no component in time. This essentially means that you can travel the speed of light as long as you aren't travelling through time. Would that mean that you aren't travelling since displacement is proportional to time? Or would this mean that you would essentially teleport? Could you control it? Most importantly, how do I get my brain to stop hurting from all of this?
Mythbusters, despite its ridiculously corny commentary, was one of my favorite shows. In case you've lived in a cave for the past few decades and don't know what Mythbusters is, I'll explain it to you: Two people, Adam and Jamie, took a bunch of questionable myths or movie stunts and remade them in real life to test and see if they actually work. It was great: explosions, car crashes, gun shots, and more.
One of their episodes was testing a myth that has to do with kinematics: They had heard that if you shoot a bullet out of a gun vs dropping it on the ground, they would fall the same distance in the same amount of time, even though one was moving much quicker. In case you didn't realize, this is a simple 2-Dimensional kinematics question (although technically it could be considered dynamics as well since they did take drag into effect).
To test this theory, they took 2 identical bullets, and simultaneously shot one out of a gun and dropped the other straight onto the floor. As you can see in the following gif, the "myth" stands. The clip is slowed down significantly, so even though it doesn't look nearly as close, they both hit the floor less than a tenth of a second apart.
If you want to watch the whole video, click this link: https://www.youtube.com/watch?v=tF_zv3TCT1U
Let's say that there's a car parked in the middle of an airfield. It's a decent size for a car, and conveniently, there's a couple big line of cones making a lane directly towards the side of the car. Somebody sees this setup, and decides to hop into their dump truck, and drive quickly down the lane, and into the side of the car. Who wins?
The dump truck. Obviously. Why? It has more mass, and therefore more inertia. But it also has more speed, and therefore more momentum.
As you should all know by now, momentum is equal to the mass of an object multiplied by its velocity, or p = mv
This means that the car, if it weighed 1 metric ton, or 1000 kg, multiplied by it's initial velocity 0 m/s, had an initial momentum of 0 kg*m/s
The dump truck, if it weighed 2.5 metric tons, or 2500 kg, multilplied by it's initial velocity 25 m/s, had a po = (2500 kg) * (25 m/s) = 62,500 kg*m/s
The law of conservation of momentum, assuming that there's no outside forces acting on the system, states that the momentum of the system before the collision is equal to the momentum of the system after the collision, or in this case, pcar +ptruck = pcar + truck since the car and truck stick together after the collision.
Now we can substitute in for momentum. (0 kg*m/s) + (62,500 kg*m/s) = vf * (mcar + mtruck) or (62,500 kg*m/s) = vf * (3500 kg)
If you solve for vf, you get vf = 18 m/s
After the collision, when the car sticks to the dump truck, the dump truck moves much slower than it originally was, even though it's fairly difficult to see in the clip. TV shows tend to like fast cuts and replays, which make it hard to appreciate the science.
You've probably noticed that on the side of your cereal box or milk carton, there's a big table of nutrition facts. In this table, it shows the quantities of vitamins, fat or sodium, but most importantly, it shows how many Calories the food has per serving. You've heard about Calories before, and know that you gain weight if you consume a lot of it, but probably don't know exactly where the measurement comes from.
A dietary Calorie is always spelled with a capital "C" while a physics calorie is always spelled with a lowercase "c". It is very important to not get these mixed up, because as confusing as it may be, you can eat so many more calories and stay healthy than you would if you ate the same amount in Calories.
Specifically, 1,000 physics calories, or "gram calories", is equal to 1 dietary Calorie, or "kilocalorie."
It's not like you'll encounter calories nearly as much as you'll encounter Calories, especially since everything related to diets and health are measured in Calories. Either way, it's still interesting to know where they come from.
1 physics calorie is the amount of energy it takes to heat up 1 gram of water by 1 degree Celsius. Not surprisingly, 1 dietary Calorie is the amount of energy it takes to heat up 1 kilogram of water by 1 degree Celsius. It makes a lot of sense that food is measured in Calories, since otherwise you'd look at the nutrition facts of a single Reese's Peanut Butter Cup and realize that it's 105,000 calories. You probably wouldn't eat that much candy if you saw that, so they crunched the numbers down to make it a little less overwhelming. Food companies do like to trick you, however: they make the "serving size" really small so that their food doesn't appear as bad as it actually is. Next time you're buying cereal, even if you're like me and don't care about the dietary facts, just look at the nutrition table and see how small the serving sizes are. I've seen a box say that 1/2 of a cup of cereal is a serving for 1 person. Think about that the next time you eat 4 bowls of cereal in a row.
So over the weekend, I've been thinking about how much worse my grades have become recently. Long story short, this got me thinking about retarding forces, and a wonderful example to share with you all.
Now let's say that there are 2 people sitting in a helicopter with their legs hanging out the side, having some lunch. One of them is ridiculously overweight, let's call him Big Mike, and the other is ridiculously skinny, let's call him Nick. Mike weighs around 300 lbs, which is the equivalent of about 135 kg. For convenience, let's just say that Nick weighs around 100 lbs, which is the equivalent of about 45 kg.
Now let's say that Mike dropped one of his sandwiches off the edge of the helicopter, and reached out to grab it, but accidentally slipped off the side. Nick, in a feat of heroism, grabs Mike, but was sadly too late to stop him, and ended up falling off the side as well.
The two are now tumbling down into somebody's backyard, where conveniently, there's a trampoline underneath the two of them. The trampoline is strong enough to stop Nick safely if he was moving at terminal velocity, but not Mike, even if he was moving at double Nick's terminal velocity.
For convenience, let's say that the force of air resistance is equal to -bv, and b = 9.8 for both of them, and they both fell for long enough to reach their terminal velocities.
As you can see, Mike would eventually accelerate to about 135 m/s and Nick would eventually accelerate to about 45 m/s. Double of Nick's terminal velocity is 90 m/s, but sadly, Mike was moving faster than that, and tumbled into the trampoline, breaking it, and died smashing into the ground beneath it.
Because Big Mike was moving faster than Nick, he broke their safety net, so Nick smashed into the ground and died too.
If only Mike had kept his gym membership, he and Nick might've survived that fall.
Recently, I've been replaying one of my favorite sci-fi video games, and came across a pretty amusing conversation.
For some quick context before I post the video, the game is in the future when humanity has advanced enough to have efficient space travel, allowing them to colonize other planets. They also advanced enough to have giant spaceships with giant guns on them. How fun. In the exact scene in the video, there's a drill sergeant yelling at 2 cadets about firing nuclear-grade armaments at other ships.
Warning: The following video contains graphic language, even though chances are you don't really care.
I just like to think of what events had to happen for this drill sergeant to have to chew out these cadets. Did this Serviceman Chung fire out multiple nukes into space while guessing his aim? It's a pretty amusing scenario, and not that unlikely either. I suppose that if we do manage to advance technology far enough, this would become an issue. We couldn't just fire willy-nilly out into space, because it might eventually hit someone. This is why when I go target shooting at my uncle's house, we shoot towards the bottom of a hill so that any missed shots don't go flying through somebody's window, they just land in the dirt.
It also makes me wonder about how much stuff is just floating around the Earth right now. We don't have rings like Saturn, but there's still plenty orbiting our planet. There's got to be paint chips off of spacecraft we've sent up, maybe a tool that an astronaut accidentally let go of while doing an EVA, and just bits of dust from comets or asteroids. Even something as small as a pebble, when flying through space at multiple kilometers per second can do quite a lot of damage to a satellite.
Well, that's just my train of thought. If you have anything to add, put it in the comments.
- 4 beliefs that make people stupid:
- Learning is fast
- Knowledge is composed of isolated facts
- Being good at a subject is a matter of inborn talent
- They are really good at multi-tasking
- The belief that knowledge is composed of isolated facts really stuck with me because of just how incorrect it is. Even in AP Physics 1, if you simply memorized all of the equations and nothing else, you probably wouldn't have passed. It's more about how the equations relate to other equations and the problem, and how they can be manipulated to get the correct answer.
- Metacognition is somebody's ability to understand a topic. Even if they memorized and know everything about it, they might not understand it at all. There's a big difference between knowing something and understanding it.
- What you think about while studying is the most important factor in successful learning.
- Deep processing is processing something by fully understanding it and connecting it to other topics rather than simply memorizing it.
- 4 things that help learning
- Minimizing distractions and maximizing focus – I need to place myself in an empty room with nothing but my work. Even then it still might not work, though.
- Developing accurate metacognition – Rather than memorizing equations, I should memorize what the equations are for and how it can relate to other equations.
- Deep, appropriate processing of critical concepts – I should relate topics to my own personal experiences more
- Practicing retrieval and application – I should learn based on practice rather than review
- 6 principles for optimizing learning
- Elaboration – I should relate topics to each other rather than simply focus on each individual topic separately.
- Distinctiveness – Just as I should relate two topics, I should also remember their differences and not combine them together consistently.
- Personal – Relating stuff to personal experiences can really help us remember them, and I have never done this in the past.
- Appropriate to Retrieval and Application – Practicing problems and reciting memorized information would probably severely improve my memory skills, which are currently close to zero.
- Automaticity – Practicing something so much that it basically becomes muscle memory. If I do this enough in high school, I won't have to worry about the transition into college nearly as much.
- Overlearning – Rather than simply memorizing something, overlearning is continuously practicing something so that my skill in it improves and I become quick and efficient at it, such as studying. I have spent years practicing procrastination, and I think that my skills in it have improved dramatically since I first started.
- 6 question generation techniques
- What were the 6 principles for optimizing learning?
- How does relating academic topics to my personal experiences improve my studying skills?
- Why does automaticity help study when it discourages deep processing?
- Would overlearning drive people to despise a topic, causing them to lose motivation and stop studying?
- How do automaticity and overlearning differ?
- When have you studied with only shallow processing?
- They provide a summary of the lecture rather than copying everything, create memory cues to help remember the information, and actively engage you in the lecture. They have the same benefits.
- I would be a part of a study group, and even though I really should, I don't think that I will. This is mainly because other people would be more of a distraction for me, and we would end up bringing each other down. I will help others out when they get stuck on a problem, but probably nothing more than that. Even with my massive procrastination issues, I'm motivated enough to get my work done well.
- Go into denial
- Keeps studying the same way
- Waits to get help until its too late
- Skips class
- Falls farther behind before while waiting to catch up
- Cram at the last minute
- Skip small or late assignments
- Give up
- Examine how you prepared and be honest with yourself
- Did you go to class and do the assigned work
- Review the exam
- Compare errors with notes taken
- Talk with your teacher
- Examine study habits
- Develop a plan
- How to raise grade
- Commit time and effort
- Minimize distractions
- Attend class
- Set realistic goals
- Don't slide
- Don't give away points
The pages of APlusPhysics.com, Physics in Action podcasts, and other online media at this site are made available as a service to physics students, instructors, and others. Their use is encouraged and is free of charge. Teachers who wish to use materials either in a classroom demonstration format or as part of an interactive activity/lesson are granted permission (and encouraged) to do so. Linking to information on this site is allowed and encouraged, but content from APlusPhysics may not be made available elsewhere on the Internet without the author's written permission.
APlusPhysics.com, Silly Beagle Productions and Physics In Action materials are copyright protected and the author restricts their use to online usage through a live internet connection. Any downloading of files to other storage devices (hard drives, web servers, school servers, CDs, etc.) with the exception of Physics In Action podcast episodes is prohibited. The use of images, text and animations in other projects (including non-profit endeavors) is also prohibited. Requests for permission to use such material on other projects may be submitted in writing to firstname.lastname@example.org. Licensing of the content of APlusPhysics.com for other uses may be considered in the future.