# Blog Having Nothing to do with Physics

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Actually a Physics Blog

## The Benefit of Anti-lock Brakes

Bob is barreling down the thruway in his truck at 40 m/s when a crash occurs in front of it. The driver wants to stop in the shortest distance possible. He slams on the brakes. Before the invention and implementation of the Anti-lock brake system, or ABS, the truck's tires would have locked up and the truck would have slid into the crash. Why? When brakes cause tires to lock up, the type of friction between the tires and road changes from static friction to kinetic friction. This decreases

## Escape Velocity and its Applications

The calculation for escape velocity is a pretty simple conservation of energy problem. K at infinity =.5mv2 = 0 because v at infinity = 0 U at infinity = GMm/r = 0 at infinity because r = infinity K=0 U=0 K=U .5mv2 = GMm/r From there it's simple algebra, and escape velocity is ve = sqrt(2GM/r) This equation's applications are seen in the exploration of space. Spacecraft need to reach escape velocity in order to not eventually crash back into the earth's surface. Some satellites are

## Why is Exploring the Ocean so Hard?

"The ocean covers 71 percent of the Earth's surface and contains 97 percent of the planet's water, yet more than 95 percent of the underwater world remains unexplored." Source: http://www.noaa.gov/ocean.html Many obstacles exist keeping widespread ocean exploration from becoming something not extremely difficult. One obstacle is the pressure under water. "The deeper you go under the sea, the greater the pressure of the water pushing down on you. For every 33 feet (10.06 meters) you g

## Torque: It makes things rotate

Torque is the tendency of force to rotate something around an axis. Torque helps you turn a doorknob, it makes a car's tires spin, it basically helps a force act in a circle. Applications of torque equations can help solve real world problems. Locations for supports for bridges can be determined by examining the effects of the torque vehicles would cause on a bridge. An engineer looking to efficiently maximize the potential for producing torque in an engine would choose electrical or diese

## Electromagnets

An electromagnet is created when an electric current produces a magnetic field. Electromagnets have multiple applications and are a popular application of magnets. Electromagnets are often used in large metal scrapyards where large amounts of metals need to be distributed quickly and efficiently. A crane with an electromagnet on its arm is perfect for this task because the crane operator can induce a current to magnetize the electromagnet and pick up metal, and then cut the current when h

## The Physics of Our Muscles

In our body, we often consciously use our skeletal muscles. Our nervous system sends an electrical signal to our muscles which affects proteins which cause our muscle to contract. Electrical energy is transmitted which begins a process of chemical energy being converted to mechanical energy. Some smooth muscles behave like skeletal muscles, while others have contractions which are regularly and methodically induced by specific cells. The actions of these cells keep systems such as the digesti

## Turning Corners with Physics

When taking corners quickly, the biggest worry most drivers should have is slipping and losing control of the car. This happens when a driver takes the corner too fast. The physics of taking a flat corner depends on the equation vmax = Sqrt(mu*r*g). mu, the coefficient of static friction, is constant, as is g, the acceleration due to gravity. Therefore, a driver trying to take a corner as quickly as possible would like to make the radius of the turn as large as possible to allow for a higher vma

## Why is There Less Noise During a Heavy Snowfall?

Is it just me or does it get quieter outside when a couple of inches of snow are falling? Actually, the answer is a combination of both. First of all, during a big snowfall, there are likely to be less people and other noise making devices outside, so there is less initial sound hitting they eardrums, without regard to any effect the snow has on sound waves. What if the amount of noise made is the same before a snowfall and during/after? Sound waves are absorbed by porous and insulat

## How is Tap Water Safe if the Supply Pipes Get Leaks?

This blog was inspired by this fact: The New York City water supply system leaks at a rate of up to 36 million US gallons (140,000 m^3) per day. Source: http://www.nytimes.com/2008/11/23/nyregion/23tunnel.html?pagewanted=2&_r=0 Our water is extensively purified, and is completely safe to drink, but how can it be safe if some of the biggest supply pipes have holes all over? Besides the full -on sanitation of the water, one part of the solution is that our water supply contains some

Hello, Anonymous AP Physics C student here, letting all you other anons know what i think and stuff. I was promised points for posting here, so here I am. I have always loved math and science, because applying these subjects has allowed me to better understand the world around me. I am hoping AP Physics C will help me understand the real world and the way things interact in it rather than a world that exists only in an engineer's dreams. I am taking this class because I love challenging my

## Rail Guns

A military application of electromagnetic force is the rail gun. A rail gun is like a regular gun in the sense that it fires a projectile out of a barrel, but it has some major differences. A regular gunpowder gun uses a projectile with a firing pin, which is hit by the gun, pressurizing gunpowder, resulting in an explosion which propels the projectile forward. This is a bit inefficient however, because a lot of recoil occurs in the gun because of conservation of momentum, and a lot of exc

## The Electrical Grid in Your Home

The electrical grid is wired in parallel. Why? The benefit of having your home wired in parallel rather than in series is having a uniform voltage rather than a uniform current. Because your home is wired in parallel, manufacturers of electrical products can set a specific resistance and know the expected current because of ohm's law V=IR, rearranged to I=V/R. The danger of having everything wired in parallel is that increasing the amount of resistors in the circuit decreases the equiva

## Pavel Time

What is Pavel time? Pavel time is the time right before a deadline when actual work gets done. How does this relate to physics? It relates specifically to Albert Einstein's theory of relativity. Part of the theory of relativity states that measurements of various quantities are relative to the velocities of observers. In particular, space and time can dilate. So, in real life, as an object approaches the speed of light, it gets squished and time slows down for the object. How does t

## Nuclear Reactions

There are two types of nuclear reactions that are very prevalent in today's society: fission and fusion. What are these reactions and how are they used? Nuclear fission is a reaction where a molecule splits into smaller molecules and excess subatomic particles, and releases energy. This type of reaction happens in nuclear bombs and in nuclear power plants. In nuclear bombs, this reaction is set off by a neutron hitting a nucleus, making it unstable and causing fission. In a bomb, this happ

## Light as a Particle and a Wave

Light is subject to a quantum theory called wave-particle duality. This theory proposes that matter exhibits both properties of a particle and properties of a wave. The experiment that shows light's wave-like properties is the double slit experiment. when light was shone through two slits close together, and a screen was placed behind the slits, the impact pattern didn't look the way one would expect a particle impact pattern to look like. After going though the slits, the light diffracted, c

## The Helicopter and its Rotors

Helicopter blades, or rotors, are what keeps a helicopter in the air, and help it get from point A to point B. The turning of the main rotor creates lift, and tilting the main rotor moves the helicopter in any direction. An interesting requirement for helicopters is that every helicopter must have at least two rotors. This is because the turning of a rotor creates torque in the direction opposing its rotation. If a helicopter had only one rotor, the rotor would spin one way, and the helicopte

## Momentum

Veritasium, a channel on YouTube, posted a series of videos showing an experiment where a bullets are shot into blocks, where one time, the bullet is shot into the center of the block, while another time, the bullet is shot off-center. The first video can be watched here: And the second here: The explanation for the result of the experiment has to do with momentum. While the second block has more energy, it has the same momentum as before, because linear and angular momentum are i

## Gravity is Weak

What? Gravity is weak? Then how am I not floating right now? This has to be a joke. It's not. Gravity is one of the four fundamental forces in our universe. The others are electromagnetic, strong nuclear, and weak nuclear forces. Gravity is the oddball in this group. It is also preventing the completion of the unification equation. While the other forces, besides E-M, have relatively short ranges, gravity does not. Gravity has infinite range, and has a bigger effect over range than o

There are two often used ways of avoiding RADAR (RAdio Detection And Ranging): Stealth and Jamming. This blog post will cover stealth. Radar can be rendered useless or less useful if the radio waves sent out by radio towers never return to the towers themselves. Airplanes today are equipped with more than one way to hide from radar. One way planes can avoid sending radio waves back to towers is by only allowing radio waves to reflect at one angle. The B2 bomber, as shown in the p

## Magnetic Levitation Trains

Magnetic Levitation (Maglev) trains are one of the ways electromagnets are used every day. Maglev trains carry passengers at speeds of 310 mph. The trains are able to reach such high speeds without falling apart partially because of their sturdy design but also because of their propulsion system. The trains are held up by magnetic forces when they approach higher speeds.the lack of physical contact with rails reduces friction to only that of air resistance, allowing the train to be more

## Crash Test...Not So Dummies

When cars get into a collision, why does it seem like half the car gets turned into debris? The answer is simple, conservation of momentum. In elastic collisions, like car crashes, the projectiles have a lot of momentum. If a head on collision occurred where the cars stayed perfectly rigid, the occupants would have a huge change in momentum. This used to happen before modern safety regulations. Modern cars are designed to "give", absorbing a large amount of momentum and keeping the occupan

## Catching up on Sleep

Every teenager has stayed up late, woken up early, regretted their decision, end then slept extra long the next night. Can a person really catch up on sleep? Numerous studies have been conducted on the subject, and what is the prevailing hypothesis is that there are two systems dealing with sleep, a circadian process and a sleep homeostatic process. The circadian process is a rhythm of sleepiness and alertness over a twenty four hour period. This clock is related to the amount of light

## The Physics of Walking

Walking is just controlled falling. Don't believe me? Take a step. The human body has its center of mass high up off the ground, so it requires a continuously acting balance system. When you take a single step, you shift your weight forward in such a way that if you didn't have a balancing system, you would fall flat on your face. At the last second, you swing a leg forward and catch yourself, regaining your balance. Taking a walk is just repeating the same motion over and over again. T

## Aircraft Carriers Float

The Nimitz class aircraft carriers currently in service for the US Navy weigh anywhere from 102,000 to 106,000 metric tons. If these gigantic ships weigh so much, why don't they sink? The way a ship floats is not only dependent on its weight. Even though the ship is extemely heavy, it displaces an amount of water which weighs the same amount as the ship. If more of the ship goes under, the weight of the water it would displace would be more than its own weight. This phenomenon causes the w

## Magnets and Their Properties

Substances are magnetized when their electrons spin in the same direction. What this does is it creates charge differences in a substance. Magnets have north and south poles. These poles dictate the direction in which the magnetic field flows both inside and outside of a magnet. On the outside, field lines flow north to south; inside they flow south to north. Interestingly enough, magnets will always have both a north and a south pole. This can be observed if a magnet is cut in half. Since