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Bogart

Railguns

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.

Bogart

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.

Bogart

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?

Bogart

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.

ezgif-4-1c3506dc29.gif.27a69bf66cff2bc34069b127b67c01c1.gif

If you want to watch the whole video, click this link: https://www.youtube.com/watch?v=tF_zv3TCT1U

Bogart

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?

MOMENTUM.gif.20ee0d18577bfba58e8ab87f9ea49df1.gif

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.

Bogart

Units of Energy

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.

Bogart

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.

59f6a88452535_Workforstuff.png.d32719b3f0807caf2a33d5e9a46a5f7c.png

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.

Bogart

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.

Bogart

Video 1:

 - 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.

 

Video 2:

 - 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

 

Video 3:

 - 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.

 

Video 4:

 - 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.

 

Video 5:

 - Don't

        - Panic

        - 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

 - Do

        - 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

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