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Lasers/directed energy weapons

Militaries around the world constantly search for improvements to their weapons technology to give them an important edge over every other country. One weapon that could provide this advancement is the directed energy weapon. Directed energy weapons “shoot” energy (usually in the form of electromagnetic or sound waves) instead of projectiles. They work on the principle of firing a burst of energy in a very small diameter at a target. This generates intense heat that can melt electronics, cause p

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Flails

The flail, also known as a mace and chain or morning star mace, was a late medieval weapon consisting of a short rod with a chain at one end attaching it to a heavy, usually spiked, ball. Flails were not used very often because an experienced enemy could easily step in close to a user making the flail useless. However the flail does have some interesting advantages that we can analyze with physics. First, the combination of rod and chain created a very long weapon that could create huge amounts

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Why trees sway in the wind

With spring weather finally here there are lots of trees that can be seen blowing in the wind. They do this because the wind pushes air molecules against the leaves and branches exerting a force on the trees pushing them to the side. The branches bend with the force of the wind then swing back oscillating in harmonic motion to gradually return to their equilibrium position. If trees did not oscillate they would snap more often because a greater force would be exerted over shorter distance and ti

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Atlatl!

After a few blogs studying futuristic weapons I think it's time to look at some ancient, even prehistoric weapons. One of the most interesting of the physics related weapons was the atlatl. The atlatl is believed to have been developed independantly on each of the six inhabited continents. The atlatl is a tool to throw spears further and faster than is possible by hand. With an atlatl a spear can easily be thrown at more than 100 mph and travel well over 100 yards. The atlatl was used in hunting

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The Physics of Tossing a Pizza

Tossing pizza dough is very important to get the proper thickness and consistency of dough to make a pizza with. It also helps with the development of better standing wave ultrasonic motors, but more on that later. Professional pizza tossers know and scientists have proven that the best way to toss a pizza from rest is in a spiral. This is because a large amount of torque is required to get the dough spinning and all the rotation it has will be created when it leaves the throwers hand. However,

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How to make a PVC powered catapult

Of the many catapult designs that can be easily made by high school students, one of the best creations in terms of ease of construction, consistency, and ease of launch. To build a simple PVC powered catapult simply create a simple square base and attach a single crossbar approximately 3 feet above the height of the base. Attach one end of a 9ft long, 1in diameter PVC pipe directly below or slightly behind the crossbar. Be sure that the PVC is in front of the crossbar. To the other end of the p

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Two-way mirrors

Ever wonder how a two way mirror works. The concept behind a mirror that you can see through on one side but not the other is surprisingly simple. It all has to do with how light is reflected on the sides of the mirror. The most important thing to realize is that there is no difference between one side of the mirror and the other. Two way mirrors work because the observer on one side sits in a darkened room while those being observed sit in a brightly lit room. Most of the light waves from the b

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Tornadoes

The physics of tornadoes is very interesting. It all has to do with pressure and angular momentum. When air is heated it expands causing the density to decrease. This decrease in density combined with the higher density air around it causes the heated pocket to rise. The surrounding air then rushes in to fill the void and a tornado is born. The tornado is perpetuated by its own angular momentum. To learn more check out http://outreach.phas.ubc.ca/phas420/p420_04/sean/

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Shoot Lightning?

Another weapon that is undergoing developmnt is a weapon to shoot lightning. This is the latest version of Nikolai Tesla's "Death Ray". The goal is to produce a weapon that can shoot electricity through the air at a particular target. The latest idea is that the weapon wil shoot a high power laser for a very short time which creates a path of ionized air (or plasma) which is a better conductor of electricity than normal air. The weapon then sends electricity along the path to the target. The ele

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Bolas

Bolas are another medieval weapon that have some very interesting physics aspects. Bolas consist of 3 balls attached to equal length strings joined together around a central axis. The thrower exerts a force on two of the balls causing them to rotate around the third. When the balls are released they revolve around the center axis until they impact there target. Then the rotational force is turned into linear force breaking the targets legs.

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Boomerangs

Boomerangs were a highly effective weapon for the natives of Australia (called aboriginals). Today people picture boomerangs as curved sticks or peices of plastic that are supposed to come back when you throw them but never do. However the returning boomerang is likely just a creative development of the far more useful non-returning type. Boomerangs were used in hunting and warfare as an effective long range weapon and for hand to hand combat. A boomerang, effectively, is to wings stuck toget

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The physics of Statues

Statues are an excellent form of art that represent specific people. Because statues must be able to stand the sculptor must consider many important physics concepts in their creation. A persons center of mass is very high on their body so an exact replica of a person standing would fall over. For this reason sculptors usually give standing figures larger feat or legs to lower their center of mass and therefore stabilize their creation. They sometimes add other figures to lean against for the

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Levitation

Most people consider levitation to be possible only in fantasy worlds. However people can make use of the power of electricity to levitate/fly under certain conditions. To levitate there must be no net force on an object while the object is not touching the ground. On Earth gravity is always pulling down so we must find another force to counteract it and push up on the object that we want to levitate. Their are four forces in nature, gravity, electromagnetism, and strong and weak nuclear forces

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The physics of Jumping

Jumping like most things requires far more physics than is commonly considered when the action is performed. The maximum height and distance of a jump are determined by three main factors, launch angle, force applied, distance over which the force is applied, and duration of the force. As any physics student can see this fits the equation P= (Fdcosθ)/t meaning that a jump is determined by the power of the jumper against the surface they are jumping from. This means that in order to increase the

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Popping Popcorn

Popcorn is one of the four main types of corn, the others being sweet, dent, and flint(indian) corn. Of these types only popcorn pops. This is because popcorn has a hull with the proper thickness to make it burst open. Inside a kernal of corn their is a small amount of moisture surrounded by soft starch. As the kernal is heated the moisture expands increasing pressure and eventually causing the hull to burst. This occurs when the temperture of the kernal reaches 347°F which causes the pressure a

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We still need NASA.

With the new federal budget finally increasing NASA's funding I think its time to talk about some of the great things NASA has done and still does. NASA created the basis for many important products that we use today including memory foam, scratch resistant lenses, and water purification systems. Some people consider NASA to be unnecessary because of the advent of space entrepreneurship with companies like SpaceX sending shuttles to the ISS and putting satellites into orbit. However NASA is stil

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Mudslides

After the devastating mudslide in Washington last month I decided to find out a little more about what causes mudslides. Mudslides occur when porous soil becomes over saturated with water and becomes to heavy for the soil beneath to support it. The mass of the soil increases as it fills with water causing a greater force to be applied to the lower layers causing the bottom of a hill to explode outward. The extra water in the soil also decreases friction causing it to slide more easily down a slo

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Faraday Cages

Faraday cages have a variety of uses in the modern world from repairing high voltage power lines to protecting government secrets. Faraday cages shield their contents from static electric fields. A Faraday cage is effectively a conducting shell that distributes any charge around the edges. As we can see from Gauss's law Flux = Qenc/E0 if we have a conducting shell with no charge inside their is also no electric flux inside. This means that you can put massive amounts of charge on the edge of the

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First Blog

1) I am interested in science and history and am reasonably good at both. One way in which I could improve is to start projects sooner. 2) I'm taking physics C this year because I liked physics last year and wanted to continue my studies in the subject. 3) I hope to learn about physics and get a five on the AP this year. 4) I am not excited about anythng specific this year becasue I don't know what we will be doing. 5) I am not anxious about anything for the same reason I am not exc

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Why heavy snowballs are better

Ever wonder why heavy snowballs fly so much further than light ones? The answer is pretty simple. First lets assume that we have two snowballs that are the same size and shape but one is twice as heavy as the other. Also we know that each will leave are hand with the same velocity since our hand can only move so fast regardless of the weight in it and the weight of a normal sized snowball will not slow it down at all. To figure it out start by drawing a force body diagram for each snowball.

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How waters properties shape planets

As we all know water changes the face of our planet in dramatic ways. Rivers can blast paths through the ground with remarkable speed making their way to massive oceans. But one of waters unique properties is even more useful in changing the shape of the earth. Unlike almost every other material water expands when it changes from a liquid to a solid. This is what causes icebergs to float. It also prevents most of the earth's surface from being covered in big rocks like other planets. This is bec

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Elasticity in PVC powered catapults

PVC powered catapults work on the principle of elasticity. Elasticity is the tendency of solid materials to return to their original shape when contorted. This means that when the top of a PVC pipe is pulled back, an elastic force will attempt to return it to its original position. This means that if the pipe is pulled back and then released the elasticity will whip it forward launching the object. There are two main measures of elasticity, the modulus and the elastic limit. The modulus is a

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Rail Guns

An electromagnetic rail gun, commonly referred to as a rail gun is an experimental weapon that could be used to fire projectiles at very high speeds. A rail gun is basically two conducting rails connected to a pulsating power supply. A bridge is placed between the two rails to complete the circuit. When current flows up one rail through the armature and down the other rail a magnetic field is created that pushes the armature toward the end of the rails. This is because the current creates a magn

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The week of Physics (10/14 - 10/18)

Hi everybody, This was a good week in physics C. We started out with Columbus day so it was a shortened week which was great. This week we focused on work, energy, and power which was mostly a review from last year which means we use equations from last year and do stuff that makes no sense using those equations and Calculus. This Tuesday Mr.Fullerton introduced us to the concept of work and we continued that concept all week. We learned how to use calc to solve more interesting problems wit

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The Physics of Space Fights - Ships

Another interesting question on the topic of space fighting is, What will the ships look like? Before we can answer this we must define the most important characteristics of a space fleet. First, the ships must be able to attack the enemy and have some defense against retaliation. Second, they must be maneuverable enough to dodge enemy attacks. And third, they must be in space. In predict that most of the ships will have weapons facing in all directions because turning in space is to difficult

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