1. reedelena's Blog

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Positive charges their electric fields are pointed out away from the charge. A negative charge their electric field is pointed toward the charge. When a positive and a negative charge are brought close together they will be drawn toward each other, they are magnetic. The electric fields never cross each other when they are magnetic. When you bring a magnetic positive charge and a positive charge together they will be repulsive, the same holds true if you bring a negative charge and a negative charge together. They are repulsive charges. The equation for electric field strength is E=Fe/q.

2. Lynn152461's Blog

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As someone who is extremely afraid of heights, it is highly unlikely that I will ever go skydiving. However, that doesn't mean I can't appreciate the physics of it. For instance, skydivers accelerate when they go down because the force of gravity is greater than the drag on their bodies. Also, the acceleration in question will always be 9.81 m/s^2 as that is the acceleration due to gravity. But when the parachute is opened, the increase in surface area creates an increase in drag, therefore making the skydiver slow down.

3. ihsseniorhill

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In physics we assume that gravity is a constant. In fact we represent this constant with the letter g and the numerical value of 9.81m/s2. Almost everything we learned this year works on the assumption that gravity is constant on the surface of the earth. There is no reason to assume other-wise after all we don't just see objects floating randomly as we take a stroll down the street. We use physics and its assumption of constant gravity- on the earth's surface- to create a lot of our technology today. But what if gravity on the surface of the earth wasn't constant? Many of our technologies would be rendered useless while other would become very amusing. So here are some fun things to think about if we all woke up one day and gravity was no longer constant.

When your alarm clock beeps in the morning waking you up for school there are many fates you may encounter. If the gravity was lower then 9.81m/s2 then you might not wake up in your bed at all. Instead you could be floating in your sleep. Just think about how much room you could save without the need for a bed! If gravity however was at a larger magnitude then 9.81m/s2 then you would be pulled down to the surface of the earth with greater force. If the force was great enough it could leave you immobile. Hey, I guess that means you don't have to go to school!

Let go to the next phase of the day. Unfortunately, most mornings I have to walk to the school in the mornings. However with a smaller magnitude of gravity I could take less steps! Although similar to walking on the moon this process would take a lot longer. If gravity all of a sudden gravity shifted to a greater magnitude, even just lifting my foot off the ground would take tremendous effort.

For those of you dieting I have both good news and bad news. A world in which gravity is always shifting means your weight is always shifting. Take note that its your weight and not your mass which shifts. Mass is a measure of the space you take up- how many particles. Weight is the measure of mass multiplied by gravity. If you were to stand in a spot of low gravity then you lost weight! however, take one step to the right and you've gained more weight in a single second then ever thought possible!

Last scenario. You're in class at school and your teacher tells you to pass up your homework. In a situation with gravity of an extremely low magnitude you could argue, "I tried to do my homework last night but it kept pushing me away." In a situation with no gravity newton's 3rd law has a field day. This law states for ever action there is a opposite and equal reaction. As you try to touch you homework, your homework pushes back at you with an equal reaction. Due to the extremely low gravity the reaction might actually cause you be pushed away. Then gravity shifts to a grater magnitude and your teacher tells you to do your homework. In this scenario you simply complain, "The force of gravity was so strong that the force I exerted on my pen was not great enough. In this process of trying to create a force stronger then the force of gravity it seems I have sprained my wrist.... both of my wrists."

4. The Blog of SCIENCE

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I attend the local Rochester parkour gym (http://www.rochesterparkour.com/) on a weekly basis. I also tend to struggle to come up with topics for my physics blog posts. But today, I had a revelation: why not combine the two. So I introduce my new series, the physics of parkour. First up is the "top-out".

A top-out is essentially a way to go from a hanging position on a ledge (a "cat"), to having your upper body above the ledge with your palms supporting you, without clambering up with your elbow in between. Here's a mock up of it:

And a video (if you only want to watch the top-out, and not all the instruction, you can go to 5:12):

It relies on three things: a solid footing, a good knee drive with the hanging leg, and of course maintaining a solid grip with your arms. When done properly, it requires a lot less upper body strength then you might imagine.

For a brief overview, it consists of three parts: building upwards momentum with your legs, building a bit of forward (but mainly rotational) momentum with your arms (the reason why they play more into rotation more than anything will be discussed), and finally transitioning to the support position resting above your palms. First, and most important, is the legs. One is planted firmly, and the other is supposed to drive upwards, in order to build momentum which will later be transferred to the rest of your body. However, friction can be tricky: the tendency of your planted leg is to slip and slip, because most people will "paw" at the wall as if they were running up it. As we know, frictional force is proportional to normal force, so you actually want to kick/jab your foot into the wall, because this will allow it to stay in place. As you're doing this, you can drive your hanging leg up, generating some momentum.

During this, you should also be pulling up/in with your hands. Simply, you want to counteract/overcome the force of your leg pushing away from the ledge, and also gather a bit more upwards momentum. However, simply due to the weaker nature of our arms, it won't contribute quite as much as our legs, which can be surprising. What is helpful, though, is the torque it creates on the body: while it is counteracting the linear momentum from our legs, it is working with the force from our legs to rotate our body over the lip, which is more beneficially, seeing as we right next to the wall to begin with. Now, with momentum built up from our knee drive and arms, and a slight rotation, our upper body will pop up and over the ledge, and rotate us into a position where we can easily re-position our hands to rest on our palms.

From there, it is usually pretty easy to swing/climb up the rest of the way. But without proper training, this technique is very difficult, because people usually rely on their arms way too much. Yet again, it's an example of something made easier through physics.

5. Stephanie528's Blog

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So everytime I need to make blog posts I always try to connect what we have been learning in physics to my favorite sport: softball. Now you might think that there are no waves in softball but I am creative and I believe I have found some sort of wave while playing softball. When people throw a softball really high it creates a giant lob that looks like a parabola. And this lob could also look like a half a wave. And if you measured from the ground to where the highest part of the ball reached, you would get the amplitude. But of course, the so called wave would never be finished you would only get to a half a wave and then the ball would hit the ground and die. But today we learned about reflection and could be applied to softball as well. When the ball hits the ground it will be reflected back at the same angle. So I the ball was thrown at a sharp angle measured to the normal line like 70 degrees. The ball would bounce back at that same angle. So while fielding, depending on how the ball hit the ground, you could prepare yourself for where the ball will jump next. Physics can improve your fielding skills.

6. OksanaZ's Blog

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We all listen to music daily and share a large appreciation for it however we don't necessarily stop to think about how music travels in sound waves or how they work. We all know that waves transfer energy but sound waves are considered mechanical waves because they require a medium in which they travel through which could be any substance or material that carries the wave along from one location to another and in this case, air would be the medium for sound waves. They travel through the air and our ears pick up the energy from these waves which vibrates against our eardrum and is converted to a nerve impulse which sends that signal to our brain. Sound waves are also considered longitudinal because the wave compression move left or right and the vibrating air particles as well move parallel to the direction the sound wave is travelling. Most of us listen to our music extremely loudly with our headphones blaring, and that means that the sound waves travelling have a high amplitude while when we listen to music as we're trying to fall asleep, its at a much lower volume to form a tranquil setting and those waves have a low amplitude, producing sound at a quieter volume. Also when listening to songs we notice that some singers have higher pitched tones than others and some lower. Having a high pitch indicates a higher frequency of a wave and those singing with a lower pitch indicate a lower frequency of a sound wave.

7. Sam's Blogging Blog of Blogginess

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Here's a tricky one, how is there physics involved in not moving?!?!?!??!?! Impossible you say? Neigh! Gravity. The only reason it's possible to not move or be constantly accelerating is because of the downward force of gravity, caused by the rotational inertia of the earth, so as long as the earth keeps spinning, you can keep doing nothing. Pretty Sweet, right?
8. Ben Shelton's Blog

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when you put a shovel on an old picnic table in your backyard and a leg of the table snaps, it's time for a new table. Problem is, the table can't be thrown away or used for firewood (some parts are just too rotted for anything put the garbage) as it is. It had to be taken apart. The first thing I did was pry off the crossbeams on the table's underside. The crowbar had to be placed at a 90 degree angle and then hammered underneath the crossbeam and pulled. The trick was to make sure the sideways pressure on the crowbar was transferred into the right place. Without something holding the main beams in place, the crossbeams would just pull up the main beams, because energy is always transferred and an object in motion (the main beams nailed to the cross beams) will remain in motion unless acted on by an outside force (my foot). With nowhere else to go, the nails where forced to separate from the board. Next I had to brake up all the beams with an ax. the acceleration of my ax would transfer onto the board, driving the head into the board. The motion I made with each swing was a half circle. sometimes the force would be so great and the wood so rotten, the energy would be transferred too fast for the board and it would break on the first try! These demonstrate two basic laws of physics: an object in motion will stay in motion unless acted on by an outside force; and energy will never be destroyed or created, only transferred. That table sure was destroyed though!

9. Faith DeMonte

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Ah yes, my favorite type of waves. Wi-Fi. Its a beautiful thing, these modulated electromagnetic waves allow you to stream movies and gain access to the internet with out being plugged in. Once only a coffee shop novelty, it can now be found in every house across the country. But how does it work? Wi-Fi can cover as much as an entire school, or building, depending on the frequency of course. Wi-Fi is a type of wave that can penetrate walls and ceilings, as well as cross rivers and high traffic areas. The Wi-Fi signal is composed of large numbers of different frequencies in order to reject noise in any of them. Also certain materials can make it harder for wi-fi to travel, and also other waves (this is the reason for channel settings) can interfere with Wi-fi too.

10. emvan2's Blog

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Like a sound wave, the waves produced by drums are longitudinal. The vibration produced when a drum is hit creates pressure waves in the air. These pressure waves describe the sound. The more the drum head bends, the volume of sound increases, a higher frequency is created and the amplitude if affected. Pitches of drums range from low frequency basses to high frequency pitches. Like a speaker which amplifies sound through the air, noise from the drums travel to our ears because of the sound vibrations and type of waves. When the vibrating drum vibrates the air molecules around it, it does so at the same frequency to produce a beautiful sound.

11. physics around us

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while bored many of us tend to listen to music, but we often don't realize how lucky we are not to have to deal with electromagnetic interference because of the newly incorporated technology such as wi-fi and error correcting systems. going back to older radios such as the analogue, many of these would have problems receiving the correct signal as there were a lot and they could not distinguish the in-band unwanted from the intended; thus, many times radio stations were disrupted or hard to dial in on.

12. zach_memmott11's Blog

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Driving involves a plethora of physics knowledge if you want to be not a good driver, but a great one. There are a lot of ways to be able to calculate the time it takes for a car going X miles per hour for X meters to stop. V=D/T is one equation that you could use to solve a problem like this, and knowing how to do this helps you know when to start to break or when to at least slow down. You'll never know how many meters your going but having knowledge like this always helps. This is all very important because being able to have knowledge of this is better than just guessing.

13. DianeTorres' Blog

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Mixtapes have physics behind them but you have to look at in a different perspective. Mixtapes have wave interference which is two or more waves in the same medium at the same time and same location. Mixtapes use sound waves and a lot of times artists who make mixtapes choose two waves that start at the same time to start their song. A new sound wave might interfere but they both continue as if they have never met and that represent constructive interference. If there is a destructive interference there will be a smaller amplitude which means it will be a softer sound for the mixtape.

14. Regents Physics

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Tibetan singing bowls are similar to humming crystal glasses. A mallet is used to vibrate the metal bowl by sliding along the edge in a circular motion. This creates a standing wave. The bowl acts as a resonating chamber, each edges' wave reflects off of the opposite side; which gives it it's unique sound. If the person controlling the vibrations does it gently enough and at the correct speed, the frequency remains constant while the amplitude will most likely increase. An increase in the speed of these pulses can create an increase in frequency and vise-versa. A difference in the medium, such as having a different size or kind of metal, can also affect the pitch of its hum. This is how Tibetan singing bowls work.
15. Abbeys Blog

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Speakers can cost hundreds of dollars to go with an awesome sound system but you can make your own as well. In order to do so you just need to learn the physics behind doing so. First electrical energy from the ipod tranfers and converts into magnetic energy which then converts to sound waves and hit against our ear drums which then converts again so we can understand them. A simple speaker can be made using a business card, wire, aux cord, a bowl and a magnet. Once you set everything up the cup in the bowl creates a louder noise and the cylindrical paper makes the noise clearer. Vibration moves up throufh the cords to the paper dishes and helps create sounds. To make everything sound better its usually better to put it on a very solid object for something to vibrate against. So next time you need a quick fix for a speaker, just use household objects.

16. claremannion's Blog

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Slinky's can perfectly represent the concepts of basic waves. First, if one person yanks the slinky to the left then quickly back once, a pulse is created. If they do this repeatedly, a wave is created. By making bigger waves, the amplitude will increase and by making faster waves, the frequency increases. If the person at the other end of the slinky decided to create waves as well, interference occurs where the two waves meet. If the waves are produced on the same side of the slinky, constructive interference will occur, creating a bigger amplitude where they meet. But if the waves are produced on opposite sides of the slinky, destructive interference occurs where displacements negate each other. By performing different experiments on slinky's, we can observe how waves work by manipulating their characteristics, observing physics in real life.

17. Physics in the real world

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When saving someones life using an AED is a good idea but only if you do it right. You put the pads on the upper right and lower left. You do this because the shock wants to go the ground. The shock comes out of both pads and wants to travel to the other pad. The heart can only take so much current before it shorts out and cannot be revived. The current that passes through the heart of an AED is just enough to get anyones heart going as long as you get there in time. After the shock is administered then the AED monitors the body to see if there are any vibrations and to check the frequency of the waves to see if they are in rhythm, it they are you saved there life, if not do it again.

18. hannahz's Blog

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Speakers contain an electromagnet which is a coil of wire that the current flows through. First, it starts with a battery and then moves into the coil of wire. When the magnet vibrates the air molecules start moving and create waves. The waves then produce the sound that you can hear. Also there is energy transfer in a speaker. For example, the phone has electric and chemical potential energy because its a chemical reaction that causes the electricity to flow. Chemical turns into electrical and then flows through the wire. When the energy flows through the wire, it moves into a coil of wire which has a changing magnetic field because the song changes the frequency of the wire. However the magnet has a contestant magnetic field and when its placed against the coil of wires magnetic field, it allows the magnet to vibrate and in the end it makes sound.

19. sputnam14

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As for many instruments resonance, or the vibrating due to an equal frequency, causes the sound. For an opera singer to break a glass with just his/her voice they would have to match the frequency or pitch that they sing at to that of the glass. When the opera singer hears the frequency of the glass, being trained they can match it to the sound that comes out of their mouth. This causes the glass to vibrate and eventually shatter once the pitch is perfectly met. For a guitar, the strings are what causes the music. When you put your finger on a string and shorten the wave length, the frequency then increases and you get a higher pitch out of that cord. This is true with most instruments such as trumpets, trombones and pianos because as you slide or press, you shorten or lengthen the wave length and in turn are changing the frequency...without physics, music wouldn't be possible!

20. anna's Blog

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the Doppler effect is when the frequency of a sound wave becomes higher the closer you get to it and then the pitch lowers as it passes you again. when an ambulance is speeding down the street with its sirens on the pitch of the siren changes as it passes you. when it is coming towards you its pitch and frequency start to increase and then reach a maximum as the ambulance is right next to you. then as it drives passed you again the pitch and frequency of the siren lowers the farther and farther away it gets from you. the Doppler effect is the difference in frequency and pitch the siren makes as it passes you.

21. mt8397's Blog

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I'll be honest: I'm not a prima ballerina. I'm terrible at balancing while en pointe. (For those of you who aren't familiar with ballet, "en pointe" means when I'm standing on the tips of my toes while in pointe shoes.) My teacher always tells me, "Put all your weight on your big toe!" And here's why:

To stay balanced en pointe, a dancer's center of gravity must be directly above the contact point with the floor. This is called static balance. The net force is zero while torque is also zero. The net force is zero when the force of gravity equals the force of the dancer pushing off the floor. (It gets painful after an hour, trust me.) The net torque is zero when the net force points through the dancer's center of gravity.

After months of pointe training. I've mastered balancing while standing still. However, I have yet to master balancing while turning. The key to good turning is making sure your rotational axis doesn't wobble. Even if you're spotting, a rotational axis is hard to see. (You can't see it!!) We've learned that in order to stand en pointe, a dancer must maintain static balance. Unfortunately, it's impossible to turn while maintaining static balance. While turning, a dancer must shift her/his center of gravity constantly, which is maintaining dynamic balance. The contact with the floor always stays focused, but the center of gravity must move in a circular pattern, much like a cone shape.

Wish me luck on mastering my turns!!

22. cyan1's Blog

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watch the ISS cross the sky. Get emails for when, where and for how long! Go to: http://spotthestation.nasa.gov/

23. Kirch's Blog

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Recently we learned about resonance, which by definition is "the tendency of a system to oscillate with greater amplitude at some frequencies than at others." This is one of the many examples of physics found within the guitar. Tuning a guitar is an example of resonance. The string's vibrations create sound waves with different frequencies. Also, when you plug in your electric guitar to the amp, you are actually making use of a physics skill! You are making a speaker. The amplifier projects the sound waves which leads to louder sound. However, these sound waves might sound a little muffled to your mom who has on earplugs. You can change the bass and the treble which alter the way your eardrums detect the sound waves. As opposed to acoustic guitars, electric guitars are electrical, so they require circuits, current, and an electrical source.

24. Amanda's Blog

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Ever since I was little, I've been interested in thunder and lightning. The lightning would always crack across the sky and that would be followed by a boom of thunder. When i was young, I neve knew why these things happened or anything about sound and light. But now as a student of physics, I know some interesting facts about these occurances.

Light and sound are both a very big part of our everday life. Without them, life would be very different. Light travels faster than sound. That's why you experience lightning before thunder. Light can travel at about 299792458 meters per second. While sound travels at about 340.29 meters per second. This difference in speed is huge. There is supposedly nothing that can travel faster than light.

If you put a lamp in a vacumn, you'd still be able to see the light it produces. If you put your iPod in a vacumn and played your favorite song, no sound would be produced. This is because sound cannot travel through a vacumn, but light can.

To this day I'm still intrigued by thunder and lightning, but knowing the science behind them is pretty cool too.

25. Rules on How to Rule the Kingdom of Physics

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Hotdog was right when she said that physics was completely nuts on the first day of physics. Physics can become overwhelming at anytime during your learning career in less than two seconds. Physics is a fine art and is shaped in many different ways. The cool thing about Physics is that it's used for practically everything; this is why physics is necessary for life! The first thing I would like to talk about are the VIR Tables. I really like VIR tables because once you get the hang of it you can calculate how much energy is running through your entire house. Another thing that is pretty interesting is that there are three different kinds of circuits, series, parallel, and mixed. All that can really help you get through this course is paying attention and asking questions. It also might help if you ask your teacher for more problems for practice. This shows dedication which is key in learning! Happy Studying!