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If you ever find yourself in Las Vegas with nothing to do, $100 to burn, and gambling isn't your forte, head over to the Stratosphere Casino/tower. At the Stratosphere, you can experience the thrill of free fall as you descend 108 floors to the ground. After taking the elevator to the top of the building, you receive a brief "safety lesson." Then you saddle into the harness, say a prayer, and jump! (Ok, this isn't true free fall. A long cord is attached to your back which slows you down for the last 20 ft of the drop.) But, for physics sake, let's say that a person jumping off the Stratosphere was in perfect free fall. What would the maximum speed of the brave yet stupid jumper be? Vmax occurs as the person hits the ground h= height of the building, ~260 meters g= acceleration due to gravity, 9.8 m/s2 Conservation of energy: mgh=(1/2)mvf2 vf=(2gh)1/2 vf= 71.4 m/s which is about 159.7mph...This is the speed the jumper would hit the ground at if the cord snapped..ouch The Stratosphere SkyJump claims that its jumpers reach speeds up to 40mph which is much different than 159.7mph! The attached cord and drag force work together to slow the person down during the jump--it's a good thing! [ATTACH=CONFIG]633[/ATTACH]

...don't forget about the Chemistry test...can't relax until after that.

As APs are nearing closer, caffeine seems like the secret to success. Staying up late takes a toll on the body, and drains you of energy. Therefore, in the morning, it is very common to see kids and adults carrying around a cup of coffee or tea for the caffeine boost. Nobody wants to fall asleep in class. For those who do consume these beverages here is a disclaimer: Beware of water heated in a clean container in the microwave. Unlike when water heats up on the stove, water heated in a microwave can reach a temperature above its boiling point, and remain in liquid phase. This is called "superheating." Normally, when the temperature of the water exceeds its boiling point, the water slowly becomes a gas. But, in the microwave, boiling is hindered by lack of nucleation sites to form bubbles. A nucleation site can be a scratch in the container, a spec of dust, or any place where there is high surface area relative to volume. Also, the surface tension of the water in the mug suppresses the growth of bubbles. When the timer buzzes, and the mug is removed from the microwave, the water in the cup may appear placid, without bubbles (So, you think that the water's temp. is below 100 degrees Celsius). You are wrong, the water may be well above its boiling point. As soon as a powder such as a sugar or teabag is added to the water, the sudden addition of many nucleation sites can trigger an explosion of froth. Instantaneous boiling is induced. This can cause nasty burns to your skin. The "superheating" of water is easily preventable. First off, do not set the timer on the microwave for very long (over five minutes). Also, you may leave a nonmetallic object in the glass while it heats such a wooden stick to add nucleation sites. Lastly, stay away from heating and then reheating the same water multiple times in the microwave. Don't let this post scare you into never using a microwave again. Superheating isn't too common unless you set the microwave timer for 20 minutes instead of two, and then come back and find a very hot cup of water. Moral of the story: be safe when using the microwave.

hmm..did you draw this

This whole concept makes me really mad...its cool but frustrating

In college, I plan to major in biomedical engineering. Biomedical engineering combines biology, chemistry, physics, and math into one field of study. The field is very broad; so a biomedical engineer usually focuses on one specialization, some of which include medical imaging, biomechanics, bioinstrumentation, genomics, robotics, clinical engineering, tissue engineering... I am not sure which specialization I will follow yet; however, I think that tissue engineering is extremely fascinating. Tissue engineers are constantly finding new ways to grow skin, bones, cartilage, and even organs. The theory behind tissue engineering and regenerative medicine is that an organ made by a patient's own cells should be easily received by the patient's body. With typical transplants (transplanting an organ from human to human or animal to human), there is always risk of rejection. As strides are made in the field of tissue engineering, the results are promising. If tissue engineers can streamline the process of growing organs, people would not have to wait on transplant lists and pray for a suitable organ to turn up. The process of "growing" organs involves many steps. One of the first steps is called electrospinning. In this process, positively charged nanofibers are transferred from a syringe which is positively charged to a spinning cylinder which has a negatively charged plate behind it (physics ) . The nanofibers travel along the electric field lines, and accumulate evenly on the spinning cylinder. After enough fibers have accumulated, the engineer stops the machine. The deposited fiber is removed from the tube; and a thin sheet is end product. The engineer uses the thin polymer to construct a scaffold. Cells are placed on the scaffold which multiply, differentiate, etc. to form the intended organ. The scaffold provides a structure for the cells to form around. Once in the body, the organ slowly develops around the scaffold. Due to the composition of the scaffold, it slowly is absorbed by the body over time, leaving just the organ in place. Ta-daa! An organ has just been made! This is a glimpse at one step in the long process of creating an organ. Many chemical and biological steps come next, but this is physics so I will stop here. All in all, three cheers for E-fields which allow super thin nanofiber sheets to form!

After laying low for awhile, cross products have suddenly became very important in our current independent unit on Magnetism. For those who may have forgotten how to find a cross product, here are some reminders. 1. Cross products are needed when the multiplication of vectors is involved in the problem 2. To find cross product of a x b [where a is (ax,ay,az) and b is (bx,by,bz)] cx=(aybz-azby)i cy=(azbx-axbz)j cz=(axby-aybx)k 3. The cross product is then written: a x b = (cx,cy,cz) [ATTACH=CONFIG]625[/ATTACH]

I really wish I could do this without killing myself. It's probably not a good idea to try.

Wow Charlie you would be the first to respond

The Law of Conservation of Energy: Energy may neither be created nor destroyed. One of the most simple transformations of energy occurs when a ball is dropped from height, h. Before being released, the ball possesses potential energy equal to mgh with m=mass, g=gravitational constant, h=height. While the ball is in motion, before it reaches the ground, its kinetic energy= (1/2)mv2 increases and potential energy decreases. When the ball hits the ground, some energy is converted to friction. So, when the ball rebounds off the floor, it will not exceed the height it was released from. Well, Disney broke this fundamental law in their 1997 film, Flubber, which was a remake of the 1961 film, The Absent-Minded Professor. In Flubber starring Robin Williams, Flubber-- aka green flying rubber, bounces to the sky when dropped from 4ft off the ground. Obviously, Disney threw the law of conservation of energy out the window to create this funny fictitious substance. Flubber, when applied to the soles of the shortest, whitest, weakest, worst basketball players, allowed the athletes to jump remarkably high. The best part in the film comes right before the buzzer of the basketball game when a player with Flubber on his shoes jumps from mid-court to do about eight somersaults in the air and fly head down through the basketball hoop with the ball for the win. Best buzzer-beater ever. I'd like to see this happen in a March Madness game. But, for now and probably forever, physics restricts both the idea and creation of Flubber. [ATTACH=CONFIG]622[/ATTACH]

...Or in colloquial terms, "My stars, is that ctenophore exhibiting bioluminescence?" Definitely colloquial, common hall-talk conversation

I saw a cool demonstration of this when I went to the Corning Museum of Glass. The slow motion part of this video shows the explosion of glass really well!

Most people think of magnets as a solids. But, think again. A "liquid" form of magnet exists. Ferrofluids contain magnetic particles in a liquid carrier, and act like a "liquid magnet." Ferrofluids do not clump together to form solids because of a surfactant, which coats the magnetic particles. The surfactant overcomes the magnetic forces between the particles and keeps the solution a liquid. A ferrofluid is primarily made of a liquid carrier, and contains relatively small amounts of magnetic particles and surfactant. Depending on the ratio of liquid carrier: magnetic particles: surfactant, ferrofluids range in viscosity and magnetization. How do ferrofluids work? When a magnetic field is applied to a ferrofluid the magnetic particles quickly align themselves along the magnetic field lines. Ferrofluids can be precisely positioned and manipulated by an external magnetic field. When a magnetic field is not present, the particles of the fluid are randomly distributed in no particular arrangement. How are ferrofluids used? Ferrofluids are applied in a variety of ways. Some ferrofluids are used as adhesives, particularly in the speaker industry. In the computer world, ferrofluids act as lubricants. For machine tools, ferrofluids come in the form of a liquid spray. Ferrofluids can also plate and protectively seal materials from the atmosphere and harmful contaminants. When correctly used, a ferrofluid can improve a product's performance. [ATTACH=CONFIG]620[/ATTACH] [ATTACH=CONFIG]621[/ATTACH]

This post gave me a good laugh The graph is the best part. I wonder how washing your hands before eating finger foods connects to senioritis?

Displayed in his videos for our current independent unit, Professor Walter Lewin has a strong interest in magnetic monopoles. Lewin repeatedly stated that proof of the hypothetical magnetic monopole would win the brilliant scientist a Nobel Prize. Because of his excitement toward this topic, I have researched a bit about the mysterious magnetic monopoles. Currently, it is believed that a magnet must have a positive, and a negative pole; the existence of magnetic dipoles has been elementary and common for years. No experimental evidence has been found to prove the existence of magnetic monopoles. However, many physicists still believe they do exist for theoretical reasons. New leads and ideas have led physicists to probe polarized rocks for magnetic monopoles. Polarized rocks buried deep within the Earth’s mantle are thought to contain magnetic monopoles. When the earth formed, and separated into chemically different layers, these researchers believe that magnetic monopoles “bound to matter that sunk towards the core.” This would explain why nobody has found magnetic monopoles in the Earth’s crust. Samples were taken from Antarctic and Arctic regions, but the elusive magnetic monopole still was not pinpointed. All in all, the race to find the magnetic monopole may never end. As the hunt stands now, physicists believe they are closer than ever to tracking down the hard-to-find magnetic monopole. Whether these monopoles are bound to matter, or travel freely through space, one can only theorize. If you want to make physics history, find the magnetic monopole. http://www.spacedaily.com/reports/Searching_for_magnetic_monopoles_in_polar_rocks_999.html

Yes, this is a very nice compilation of the unit! It definitely helped me study for the test on Friday!

Circuits with resistors: In series: Req=R1+R2+R3+R4+... I=I1=I2=I3=I4=... V=IR1+IR2+IR3+IR4+... In parallel: 1/Req=1/R1+1/R2+1/R3+1/R4+... I=I1+I2+I3+I4... V=V1=V2=V3=V4=... Note: Replacing resistors in parallel with one resistor of equivalent total resistance is very useful when analyzing circuits Circuits with capacitors: In series: 1/Ceq=1/C1+1/C2+1/C3+1/C4+... Q=Q1=Q2=Q3=Q4=... (Conservation of charge) V=V1+V2+V3+V4+... In parallel: Ceq=C1+C2+C3+C4+... Q=Q1+Q2+Q3+Q4... (Conservation of energy) V=V1=V2=V3=V4=... After a long time, a capacitor acts like an open spot in the circuit; current through the section of the circuit with the capacitor= 0 A RC Circuits: Time constant=RC, or Greek letter tau I=-dQ/dt When a resistor and capacitor are in parallel, voltage drop across resistor=voltage drop across capacitor. When a resistor and capacitor are in series, current is the same through the resistor as through the capacitor. Charging RC Circuit: Current decreases over time. Charge on capacitor and potential drop across capacitor increase over time. *In the long run,VC=VT (V-terminal=V-capacitor) *I=(VT/R)e-t/RC *Q=Qf(1-e-t/RC) *Qf=CVT Discharging a capacitor: Current flows from the positive plate of capacitor to the negative plate and through the resistor. Current, charge, and voltage decrease over time. *I=I0e-t/RC *Q=Q0e-t/RC *I0=V0/R=Q0/(RC)

Faraday cages shield their contents from Electric fields. How does this work? Charge is distributed on the exterior of the cage, so that the Faraday cage acts as a hollow conductor. Therefore, since charge is only around the outside, the net charge inside the cage is zero; and, the E-field is zero inside the Faraday cage. But, what use is a Faraday cage? Well, this video excerpt from National Geographic's television show "Doomsday Preppers" will give you a whole new perspective on the value of Faraday cages and their potential value for the end of the world. When the end of the world does come, do you want your beloved electronics to be spared from electromagnetic radiation? If you are concerned, stop by the local thrift store like this woman and invest in a Faraday cage.

Physics separates the good from the great goalkeepers. 1. The Understanding of Momentum- A goalkeeper must keep his weight shifted forward, standing on the balls of his feet. When a shot comes, the goalkeeper will try to save the ball while moving forward. Therefore, due to conservation of momentum, any rebounds will deflect away from the goal. A flat-footed goalkeeper (weight on heels) will deflect shots backward, into the goal. 2. The Analysis of Vectors- While preparing for a shot, a goalkeeper must analyze vectors at all times to determine where he should stand. Given that a forward from the opposing team has the ball on the end line of the field, it is improbable that he will shoot the ball, because he has no angle. So, in this situation, the goalkeeper should stand a step or two off his line, toward the back of the goal, to prepare for a cross. 3. The Maximization of Impulse- The best goalkeepers purchase the most expensive goalie gloves. Why? One reason is that they can afford them. But, also, the most expensive goalie gloves are made of the softest foam, with premium cushioning in the palms. This foam "absorbs" the shot for a greater period of time (maximizing impulse); so, less rebounds are given up. Cheaper gloves are made of tough foam which decreases impulse, making it harder to hold on to the ball. 4. The Knowledge of Torque- On breakaways, when the opposing forward is dribbling to the goal uncontested, it is up to the goalkeeper to make a save. A great goalkeeper will strip the ball from the forward's feet, and send the player flying. How is this done? The goalkeeper slides out on the grass, attacking the ball low. Since torque is greatest when applied further from the point of rotation, the low force at which the goalkeeper hits the attacker with causes the attacker to spin and fly into the air. Yeah torque!

I saw this on a different day, and the men were lifting large spherical boulders above their heads. It is hard to imagine such strength!

The only solution is to embrace the physics

I am definitely running through the rain too. In the spring, we will most likely have many opportunities to test this question, "Is it better to run or walk in the rain?"

I never thought about this from a scientific perspective, very cool!

While studying for our midterm on Mechanics, I came to this brilliant realization. Realization: Physics with calculus is a lot easier when you know calculus Ok, this may seem like an obvious statement; but, when it clicks, it feels good. As I looked over some Mechanics Free Response problems involving derivations with drag force, I realized that they are not so bad after all. Now that all of us Physics-C students should understand integrals, differential equations, and integrating with natural logs, the Mechanics Free Response problems with calculus should seem manageable. So, for all of you who have acquired a phobia of drag force, take another look at the problems. It might surprise you that your background in calculus may cure your fear. Don't let drag force hold you back ; have confidence in this previously difficult concept!

This guy has some pretty nice drawings...I wonder why he chose to draw the pink light as a pink sheep