• entries
10
13
• views
185

## Bees?

There's a common myth that bumble bees shouldn't be able to fly because of the size of their bodies. It's not entirely certain where this myth comes from, but mostly it's because, for whatever reason, someone making these calculations didn't take into account all factors.

The wings of a bumble bee bend and move back and forth in addition to up and down. This is meant to create vortices above the wing such that the "eye" of the vortices have low pressure compared to the surrounding air, which allows the bee to fly. This concept is similar to how a plane flies in that the low pressure above the wings creates a force called lift; when air moves faster, the pressure of the air decreases. The actual way bees and planes produce those low pressure areas are different, of course; planes don't create vortices but are shaped so that the air above the wing travels faster than the air under it.

So in conclusion, there's a physics explanation for everything--including the flight of a bumble bee.

I think almost everyone has seen a slinky “slink” down a flight of stairs. At the top of the stairs, the slinky has stored potential energy and won’t move until someone acts on it. It’s not until someone begins the slinky’s movement does it begin to move, converting that potential energy into kinetic.

Each time the slinky falls from one step to another, more gravitational potential energy is changed to kinetic. But not only that, energy is transferred along the slinky in the firm of compressional waves which travel along the metal coils, causing it to stretch and compress.

Of course, since it's in motion, the slinky also develops momentum. The horizontal component of the momentum is what keeps it traveling down the stairs; if the stairs were wider and the slinky couldn't reach the end, it would stop moving, but when it is carried over the edge of the stairs, more and more gravitational potential energy is converted to kinetic and the slinky keeps going until it reaches the bottom.

## Why We Lower the Third

I've been finding that most (all?) of the things Mr. Springstead tells us in band have a reason grounded in physics. For example: when playing a major chord consisting of the root, third, and fifth, he often tells us the third note should be slightly lower.

Notes that sound "good" together, such as the notes of a basic major chord, sound that way because their wavelengths "meet up" at regular intervals. Mathematically, we can look at the ratio of each note's frequency. The ratio of C4 (middle C) to G, the fifth note of a C major scale, is (approximately) 3/2, so every third G wave meets up with every second C wave. The ratio of C to E is approximately 5/4. But in reality, that ratio is slightly off. 329.63 Hz, the frequency of E4, divided by 261.63, the frequency of middle C, is actually 1.25991. (Likewise, the frequency of G4 divided by middle C is 1.498.) Clearly, none of these ratios are perfect, but the third of the notes is slightly more off than the fifth with a percentage difference of 0.79% vs. 0.133%.

And so, to correct this (barely perceptible) problem, we try to play the third note slightly lower than normal.

## More Stuff in "The Martian"

One of the cool things about The Martian is "seeing" physics in action somewhere other than our planet. In most physics examples, we have things like friction or air resistance to contend with; after all, friction is everywhere. When we were first learning that an object with velocity but absolutely no net force acting on it would just keep moving without slowing down, it didn't seem to make sense at first (at least it didn't to me)--because every object we'd seen moving had been experiencing friction or air resistance.

But space is a pretty good vacuum; there's almost nothing out there to brush against and create friction. In the novel, Hermes experiences constant acceleration on its journey from Mars back to Earth, and, as a result, its final velocity was huge. Nothing was really slowing it down, so it just gathered more and more speed until the month before it was the reach Earth, as at that point it was traveling so quickly it need that entire month to decelerate enough to slow down to Earth's speed. Cutting the acceleration wouldn't stop the craft's velocity; it would continue traveling at its speed until it began to accelerate in the opposite direction.

Of course (spoilers) Hermes doesn't decelerate, instead deciding to do the "Rich Purnell Maneuver" and continue to accelerate past and around Earth, using the pull of gravity to adjust their course and head back to Mars. Its constant-thrust ion engine, which allowed Hermes to constantly accelerate, made it the spacecraft thing fast enough to get to Mars in time to bring food to Mark before he starved.

## The Actual Blog Post About "The Martian"

I recently wrote a blog post about intonation and constructive interference and posted it under a title having to do with Andy Weir's novel The Martian that I'd initially written as a joke because I had no idea what to write about in my post at first. But after posting that one, I realized there were actually a bunch of physics things I could talk about in the book.

I'm assuming a lot of people have read the book or seen the movie but just to be safe I'm going to talk about something that happens near the end (spoilers ahead).

When the MAV launches from Mars with Mark Watney inside, he ends up way of course and sixty-eight kilometers from Hermes. The MAV had no fuel to try to redirect its course, so Hermes attempted to use the attitude adjusters to get closer, but steady, powerful engines meant Hermes would approach the MAV at far too high of a velocity to get Watney and they didn't have enough fuel to slow back down. So instead, Watney and Commander Lewis came up with a plan to open up the vehicular airlock in order to let out the air from the ship into the vacuum of space. It's Newton's third law in action: the force of the gas being expelled from the ship creates an equal force in the opposite direction. It accelerated Hermes at twenty nine meters per second squared so that their relative velocity afterwards would be thirteen meters per second instead of forty two, as it would have been using the attitude adjusters--much more doable.

## Physics of "The Martian" From a Very Basic Point of View Because Andy Weir is a Million Times Smarter Than Me

Today in rehearsal, Mr. Springstead was trying to get us to play as loud as we possibly could at a particularly climactic part of the piece. Unfortunately, when trying to play that loudly, our intonation usually goes pretty wonky. He had this advice for us: "Playing in tune with everyone else makes you seem louder, so you don't have to work as hard to reach that volume."

Which is mostly true--except for the fact that we don't "seem" louder. When our sound is perfectly in tune, the wavelengths of the sound we produce are identical (or pretty close) which creates constructive interference.

So we don't just "seem" louder. We really are louder when we play in tune. (Realistically, though, having the entire band play entirely in tune is pretty difficult....)

## Car Tires

When we took my older sister to college for move-in day, the tires on my mom's car were extremely worn out. The car was packed with all of my sister's stuff, meaning it had more mass than usual, and, unfortunately, it was raining that day.

My mom was careful to drive really slowly, knowing that the car was more likely to slip due to the rain and the bad tires; the increased mass also meant increased inertia to an already rather massive car, meaning it would be harder to stop. Eventually, as we approached a busy intersection, the light turned yellow and so my mom tried to stop. Much to our horror, we weren't able to stop fast enough and literally slid through the intersection under a yellow-turning-red light. The tires, worn way too smooth, couldn't produce enough friction against the wet road to cause a net force large enough to counteract the inertia and decelerate the car in that short time span.

Luckily, we made it through unscathed, but that's why good tires are really important. Especially if you're driving in the rain.

## How to (Properly) Tune a Flute

We've all probably seen the tuning pegs on string instruments that tighten or loosen the strings to change the pitch. Wind instruments, however, clearly don't have tuning pegs; pitch can be adjusted multiple ways on a instrument such as the flute, but the primary way is to adjust how far the head joint extends from the rest of the instrument. As physics, we know that objects resonate at a fundamental frequency, and for flute (which, oversimplified, is just a close-ended tube) this is when there is a node at that closed end and an antinode at the opened end.

Knowing this, it makes sense that if a flute is too sharp, you should extend the head joint further out; that way it will resonate at a longer wavelength and a lower pitch. If it's flat, do the opposite. Other things, such as speed and direction of the air and temperature, can also affect pitch, but not as much as the length of the instrument. And unless you're really out of tune, these changes are pretty minor (no pun intended) from just a quarter of a centimeter to just a millimeter or two.

Of course no one who doesn't play the flute has any particular interest in how to tune one, but making that connection in physics last year has really helped me remember which to direction to adjust when I'm in band because I usually forgot, and if one person's out of tune, the whole section sounds out of tune.

## Getting the Most Out of Studying

Video 1:

A 1. Learning is fast

2. Knowledge is composed of isolated facts

3. Being good at a subject is a matter of talent

B Personally, I know I can sometimes have a bit of a defeatist attitude when it comes to math and science because subjects like English and history come way easier to me. It's good for me to keep in mind that a large part of academics is studying and practicing, not just giving up if it doesn't come easily.

C Metacognition is how aware you are that you understand the material so that you can study as much as you know you need.

Video 2:

A The most important factor in successful learning is how you think about what you’re studying.

B Deep processing is thinking about the significance behind a concept, not just thinking about the concept itself.

C Maximizing focus: I need to avoid switching between social media and other tabs while I’m on my computer doing homework or watching videos (and I especially need to avoid looking at my phone).

Using accurate metacognition: Reading the textbook doesn’t necessarily mean comprehending the concepts; I should be productive and work through things I don’t understand rather than just going through the motions.

Deep processing of important concepts: Knowing an equation relating to kinematics doesn’t mean I understand how to apply it to different situations or what they mean. Memorizing equations and definitions isn’t a productive use of my time.

Practicing retrieval and application: I should be able to figure out how to apply the concepts I’ve learned to diverse situations, which I can learn to do by practicing examples.

Video 3

Elaboration: I can make associations between two types of motion or examples that have similar properties.

Distinctiveness: I can distinguish different topics from each other by comprehending how two concepts are different from each other because otherwise I could mistake one concept for another.

Personal connection: Significant events that I can relate to a physics concept will make it more likely that I remember that concept.

Appropriate retrieval and application: Practicing applying knowledge to different problems will help me learn how to successfully apply different concepts to different situations.

Automaticity: Instead of getting work done just to do it, as I usually do with my other homework, I need to aim at creating a new studying system that will actually help me to comprehend the material.

Overlearning: I should aim to have the material understood days before I take the test so that I have time to review even more.

Video 4:

A What is “shallow processing”?

How do concept maps help deeply reinforce information?

How can practice problems be used to practice recalling knowledge?

Why is taking notes by hand preferable to notes on a computer?

How is taking quick, brief notes different from trying to record the whole lecture in terms of levels of processing?

Give an example of a time when practice tests have helped you improve your metacognition.

B Notes taken on video lessons should be brief, not just a recording of the entire video, and you should be thinking about what is being said instead of just mindlessly recording it. Concentration is important, and so you shouldn’t be pausing and switching between computer tabs. The video format is beneficial in that you can pause and record important information you missed immediately and don’t have to write so quickly that you focus on writing instead of understanding the material.

Video 5:

A If an exam goes poorly, avoid panicking or doing into denial.

B Positive steps to take after failing an exam include identifying how you prepared for the test and acknowledging your mistakes, going over the exam to see what you did wrong, analyze your weak area(s), check you missed in your notes, and improve your study strategies.

C Put in the time you need, have as few distractions during studying as possible, attend classes, set yourself realistic goals, don’t “slide” by dedicating time to one class over another, and be attentive of details that would be easy to lose points over.

Even though I find math and science to be fascinating, I consider myself more of a humanities person than a STEM person. In my free time, I do a lot of reading--mostly fiction, but some nonfiction too--and I've worked at the Irondequoit Public Library for over two years now as a page.

Ever since I was little, I was somewhat obsessed with outer space and wanted to be an astronaut. Now, I've decided maybe being an astronaut isn't for me, and I don't feel I have the knack for math and physics to work for NASA and study space, but I've decided to stick with physics anyway; it can be extremely interesting and exciting and could help me write more accurate science fiction novels if I wanted to (haha).

The workload this year seems pretty daunting and I'm worried I'll fall behind. Or just not understand the material. At the same time, I'm oddly excited for the challenge and for this opportunity to learn some (hopefully) cool stuff. I guess we'll see how it goes.