# pressure

### Improved video for deepest fish discovered

Few fish can survive the immense pressure of living in the deep sea. The Mariana Trench can reach around 36,200 feet deep with pressures of over 1,000 atmosphere. Scientists have placed landers at various depths ranging from 16,400-34,750 feet along the walls of the trench and have discovered what appears to be the "World's Deepest Fish". The fish was found at 26,872 feet which is estimated to be near the lower limit for bony fishes (of 27,600 feet). This newly discovered fish has what look like wings and tentacles. The video below was captured by the Hadal Ecosystem Studies expedition (HADES…

### The Science Behind Gliding Paper Airplanes

tags: The Science Behind Gliding Paper Airplanes, physics, teaching, flight, pressure, paper airplanes, streaming video Do you need a fun, hands-on experiment for your physics classroom? This video shows how a group of high school students, led by a terrific teacher, made origami paper airplanes from phone book pages that glide on a wave of air and what they learned from this experience. Magnificent.

### How big of a balloon do you need to get to 120,000 feet high?

I am still thinking about the Red Bull Stratos Jump. Sorry, but there is just tons of great physics here. Next question - how big of a balloon would you need to get up to 120,000 feet? I am not going into the buoyancy details of Archimedes Principle - I think that was covered fairly thoroughly with the MythBusters floating lead balloon. However, in short, here is a force diagram for a floating balloon. For a floating balloon, the buoyancy force must equal the weight of the whole thing. It turns out that the buoyant force is equal to the weight of the gas (or fluid) the object displaces…

### Bath-Time Fluid Dynamics

SteelyKid's every-so-often bath was last night, and as always, she was fascinated by scooping up water in a hexagonal cup thing that's part of one of her bath toys, and watching it drain out. Which is completely understandable-- not just because she's a baby, but because there's a bunch of physics at work, here. I realize this is trampling on Rhett's territory, but I made a little video showing the physics part (in the sink, not the tub, because I don't want to have the pay the therapy bills that would come from posting video of SteelyKid in the tub): The explanation is laid out in the video…

### Pressure demo: suction

How does a suction cup work? It is all about the atmosphere. Here is a demo. Take some type of "suction cup" device. In this case, I used a toy dart. Stick it to something smooth and lift it up. Like this: What lifts up the metal block? The atmosphere. Diagram time: But this isn't a very realistic diagram. Actually, the suction cup would be pushing down on the block because the force from the atmosphere would be too large to balance with the weight. Let me put some numbers in here. Suppose this is an aluminum block - I just going to pretend it is 4cm on a side (and a cube). In…

### Why do your ears hurt underwater?

This is a topic that I am going to talk about in my physical science class. Might as well make a post about it, right? Here is the deal. You are in a pool. You drop a quarter in the deep end and swim down to get it. I know the first thing you are going to ask: Why do I have a quarter in the pool? Does it matter. What matters is that your ears are killing you. Boy, that hurts. Why do your ears hurt and what can you do about it? Pressure and depth When you put a fluid in a gravitational field (like on Earth), the pressure in that fluid (or gas) increases as you go down. Why? There are…

### Vacuum Spider-Man

Check out this thing. That is where the guy (Jem Stansfield of BBC's Bang Goes the Theory) shows how he built this thing. Here is part 2 where he uses it to climb a building. Here are some questions: Why does it not matter how powerful the vacuum is? How does a vacuum cleaner work anyway? How does the vacuum cleaner work? I know this is not HowStuffWorks.com, but I guess I should show some stuff. The cool thing about a vacuum cleaner (think shop vac so that I don't have to deal with the brushes) is that it is just one thing - a fan. The fan essentially moves air out of the vacuum part of…

### RP 5: MythBusters: How small could a lead balloon be?

On a previous episode of The MythBusters, Adam and Jamie made a lead balloon float. I was impressed. Anyway, I decided to give a more detailed explanation on how this happens. Using the thickness of foil they had, what is the smallest balloon that would float? If the one they created were filled all the way, how much could it lift? First, how does stuff float at all? There are many levels that this question could be answered. I could start with the nature of pressure, but maybe I will save that for another day. So, let me start with pressure. The reason a balloon floats is because the air…

### RP 4: More on the movie Up! (or Upper)

So, analysis of the movie Up is pretty popular in the blogosphere. Figure I might as well surf the popularity wave. So, I have a couple more questions. The most important thing to estimate is the mass of the house. I am going to completely ignore the buoyancy of the house. I figure this will be insignificant next to the buoyancy needed. Anyway, let me go ahead and recap what has already been done on this in the blogosphere. Wired Science - How Pixar's Up House Could Really Fly - from that post: First, they calculated (seemingly correct) that the buoyancy of helium is 0.067 pounds per…

### Energy in an exploding water heater

The more I think about the last MythBusters' exploding water heater, the more cool things I see. How about I look at the energy of the explosion. There are three things I can look at: How much energy went into the water heater from the electric source? How much kinetic energy did the water heater have right after the explosion? How much thermal energy did the water and water heater have? How much gravitational potential energy did the heater have at it's highest point? Hopefully, I can show that the energy in from the electric source is greater or equal to kinetic plus thermal. Also, the…

### Physics and the movie UP - floating a house

I haven't seen the Pixar Movie "Up" yet, so don't spoil it for me. I have, however, seen the trailer. In my usual fashion, I have to find something to complain about. There is this scene where the old man releases balloons out of the house. What is wrong with this scene? Also, would that be enough balloons to make the house float? Here is a shot of the balloons coming out of the house. Ok, I was already wrong. The first time I saw this trailer I thought the balloons were stored in his house. After re-watching in slow motion, it seems the balloons were maybe in the back yard held down…

### Physics of the Water Rocket

I said I would come back to this, and I am. I am a man of my word. Yesterday, I posted a link to a video of this really cool water rocket thingy. How does this work? What is the physics going on here? I think this can be best explained with the momentum principle. Let me start by pretending like I have some object that shoots out a piece of water (or really it could be anything). Also, let me pretend like this is in space ore something where there are no external forces. Above is a before and after picture. Initially, there is something (the box) with water inside. Through some process…

### Word Police: Use of the word pressure

I know I should just let go, but this is what makes me, me. I understand that there are terms in physics (like for instance 'pressure') that are used in all sorts of ways in common language. The problem is when someone tries to explain something scientifically and misuses a word. Pressure means something. It is the average force per area due to collisions of a gas or liquid on a surface. Really, you can see a good animation of this, I have a link and explanation when [I talked about MythBuster's Lead Balloon](http://scienceblogs.com/dotphysics/2008/09/mythbusters-how-small-could-…). So,…

### MythBusters: How small could a lead balloon be?

On a previous episode of The MythBusters, Adam and Jamie made a lead balloon float. I was impressed. Anyway, I decided to give a more detailed explanation on how this happens. Using the thickness of foil they had, what is the smallest balloon that would float? If the one they created were filled all the way, how much could it lift? First, how does stuff float at all? There are many levels that this question could be answered. I could start with the nature of pressure, but maybe I will save that for another day. So, let me start with pressure. The reason a balloon floats is because the air…

### The Sky is Falling (as always)

One of my daughters was just reading Chicken Little to me. I don't know if you are familiar with Chicken Little, but she is a chicken that runs around telling people "The sky is falling". In my normal fashion, I started thinking about the plausibility of this. What would fall? What would you look for? Then I figured it out. The sky IS falling. It is ALWAYS falling and it has always been falling. What is the sky? I am assuming the sky is the air. I will treat the air as a gas of single particles (which it isn't, but that's ok). So, why does this sky (air) do what it does? If you…

### Was there Ever Liquid Water on Mars?

People love to speculate that Mars was once a great place for life to form, and claim that there is plenty of evidence that there used to be oceans and rivers there. But this isn't true. People used to claim there were big Canal-like features on Mars, and used this as evidence that Mars was very wet. It was later realized that these weren't canals, but rather geological features caused by impact craters from astroids. But more recently, people have been claiming that images like the one above are examples of dried-up riverbeds. But this turns out not to be the case. When we take a closer…