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  1. username

    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/
  2. username

    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.
  3. username

    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 slope. Mudslides are most common in areas with porous soil which is usually caused by powerful storms t
  4. 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 time (meaning power increases)
  5. username

    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 bright room are reflected back but some get through the mirror and into the dark room. Very little li
  6. The final aspect of space fighting that I will discuss here is attacking another planet from space. Once we have destroyed or gotten past the enemies fleet an invasion force would attack the planet that they wanted to conquer. Attacking from space would be tremendously useful. It would be a simple matter to toss large aerodynamic "spears" down at the enemy. Due to conservation of energy, the gravitational potential energy the projectiles have at launch would be converted to kinetic energy in the spear causing our weapon to create devastating craters whenever they landed. Although there would b
  7. 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 to be practical and having guns in all directions will make this unnecessary. Making the ships maneu
  8. If humans develop colonies we must plan for the possibility of armed rebellion/takeover on both sides. To prepare for this we should look at how space battles would be fought. First of all, explosives could not be used. Explosive devices, nuclear of conventional, are effective because they produce a shock wave that destroys the surrounding area. In space there is no air to push away so the energy of the explosion would dissipate harmlessly. Instead humans would likely use kinetic impactors, or lasers. Kinetic impactors are basically bullets that are shot at very high velocity toward enemy ship
  9. username

    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 of force since a small acceleration at the center creates a large velocity on the end. Second if an
  10. 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 because when liquid water seeps into the cracks in a rock and freezes it expands cracking the rock and
  11. 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. The forces of gravity and drag act on each snowball. Note that the force of drag is equal for eac
  12. username

    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 shell without having any charge make its way inside. This is very useful for people working with hi
  13. 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 still relevant because they push the boundaries of what is possible, which currently means sending peopl
  14. 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, after the dough is spinning when the tosser wants to toss it again they should use a semi-elliptical
  15. username

    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. Of these gravity is by far the weakest. Strong nuclear forces, fusion, provides the sun's energy a
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