Electric Bugaloo

DC, or direct cuurent, circuits draw a constant current from a battery. DC currents require a battery, a conductor (such as a wire), and some form of resistance (in this post, the resistance is the light bulbs).

Series Curcuit:


Series circuits have only one path that the current follows. In series circuits, the total resistance is equal to the sum of the resistances of each resitor. Also, the current is the same througout the entire circuit. However, the voltage drop depends on how much resistance each resistor has. In this example, all the light bulbs have the same resistance, so the voltage drop across each is the same. The total voltage is equal to the voltage drop across each resistor. Ohm's law states the the current is equal to the voltage divided by the total resistance. In other words, the more resistance is added, the lesser the current is. The more voltage is added, the greater the current is. If one bulb was removed, the rest would go out. The filaments in the bulb connect the circuit. If one is removed, then the circuit is broken, so no current is drawn.



Parallel Circuit:








Parallel Circuits have multiple paths. To be purely a parallel circuit, all of the resistors have to be on their own path after the circuit splits into those paths. In parallel circuits, the total resitance is equal to the reciprocal of the sum of the reciprocals of each resistor's resistance. In this case, the more resistance is added, the lesser the total resistance is. The current in parallel circuits is equal to the sum, of the current in each path. Voltage drop is the same throughout all the resistors in the parallel circuits. The more voltage is added, the greater the circuit. The more resistance is added, the greater the current, also. If one bulb is removed, the others would still be on. The circuit would not be broken for the other bulbs.


Series and Parallel Combination Circuit:


Combination circuits have both series and parallel circuits. The total resistance is found from finding the total resistance of each section. In the example above, a parallel circuit is connected in series with another resistor. First, one should find the resistance of the parallel circuit, then add that to the resistor that is connected in series. The voltage drop in the series portions of combination circuits is added, but in the parallel portions it is the same. In the series portions, the current is the same, but in parallel portions, it is added. If one bulb was removed, everything that is connected in series would turn off. I in my diagram, if one of the bulbs in the parallel portion was turned off, then the others would still be on. If the bulb in the series was removed, then the other would turn off because the circuit to the parallel bulbs would be broken.

Cube Runner Ferris Wheel

Just in from the labs of SAM Group LLC some the latest and greatest in Ferris Wheel Technology: The Cube Runner Ferris Wheel. This is no ordinary Ferris Wheel. Spin around at a staggering 2.2642 meters per second! Make one full rotation in just 1.11 seconds! Spin upside down, rightside up, and everything in between! So climb aboard, strap in, and hold on!

https://sites.google.com/a/parishepiscopal.org/physics-honors/amusement-park/team-5

Ferris Wheel on Prezi

Through Lazy Eyes

Contrived photo of a converging lens.

The photo is the image of my Emmitt Smith pennant through my old glasses. I had strabismus, also known as lazy eye, when I was younger. At this point in my treatment, the lens for my affected eye only was used for magnification. The image through this lens is larger. It is also upright. The image appears on the same side as the object, which makes it a virtual image. The lens for my affected eye is a converging lens. Only converging lenses can have virtual images that appear larger than the actual object. The fact that the image is virtual and larger also means that the pennant is closer to the lens than the focal point of the lens. Since the image is upright and larger, the magnification of the lens is greater than one and positive. In research, I found that most strabismus lenses are farsighted lenses. Farsighted lenses are converging lenses, so it checks out. This lens is a perfect example of how converging lenses change the distance and height of an object's image.

Fastest Stuff in the Universe: The Electromagnetic Spectrum

What goes at the speed of light? Well, a few different things actually. The Electromagnetic Spectrum is the group of types of radiation that goes at the speed of light. These types pf radiation are also known as waves. When high energy objects move at high speeds through space, they give off these electromagnetic waves. The most unique characteristic of these waves is the way it travels. Electromagnetic Waves are the only waves that do not need a medium, also known as molecules to travel through. They can travel through a vacuum. There are seven types of these waves. The waves all travel at the same velocity (the speed pf light). However, where each type of waves differ is in their wavelength, which affects their frequency and energy. The shorter the wavelength, the higher the frequency and the more energy there is.The waves with the longer wavelength are radio waves, followed by microwaves then infrared waves. Visible waves are next with a shorter wavelength, then ultraviolet rays. X-rays have a shorter wavelength than ultraviolet rays. Finally, coming in with the shortest wavelength, highest frequency, and most energy are gamma-rays.

Infrared waves are low level light that is emitted by objects too cool to radiate visible light. Infrared waves are not visible normally. However, they are visible using special cameras that "see" infrared waves. The wavelength of infrared waves varies between 10e-6 and 10e-3 meters long. The frequency varies between 2.481e14 and 3.171e11 Hz. Infrared waves are used for detecting low level light. Thermal imaging cameras are really infrared wave detectors. these types of cameras are used in many forms. Night vision goggles are infrared light detectors. Also, these cameras are used in telescopes to see through the dust around stars, such as nebulae, and see the stars themselves.

Image from http://missionscience.nasa.gov/ems/07_infraredwaves.html

Another type of waves are gamma-rays. Gamma-rays have the shortest wavelengths, from 5.577e-12 meters and shorter. They have the highest frequency, from 5.376e19 Hz and higher. Gamma-rays are only emitted by the hottest objects in the universe, such as pulsars, neutron stars, supernovas, and the areas around black holes. They are detected on Earth in nuclear explosions, lightning, and radioactive decay. Gamma-rays are used in radiation therapy. Also, they are used to map out galaxies and supernovas. Gamma-rays can even show what molecules on planet's surface are made of.

Image from http://missionscience.nasa.gov/ems/12_gammarays.html

And, as always, a Tagxedo of the seven types of waves:

Introduction information: http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html

Information about infrared waves: http://missionscience.nasa.gov/ems/07_infraredwaves.html

Information about gamma-rays: http://missionscience.nasa.gov/ems/12_gammarays.html

Wavelengths and frequencies: http://lectureonline.cl.msu.edu/~mmp/applist/Spectrum/s.htm

Energy and Cannons

I'm back for yet another awesome post! My class decided to write a post about Energy and Conservation of Energy in real world example. We also decided that we should use online tools, such a Glogster here, to create a story around the example. So, let me tell you a story about a freshman physics student who used his knowledge for a good cause...

Tools used (also stated in the Glogster):

Glogster

Equation Editor

Cosketch

Physics Mythbusters

This new lab was quite possibly the best lab yet. As you can see from the title, we attempted to "bust" two different myths about the general facts of physics, using tools such as video and online drawing tools. I will explain what the myths are in each myth's section. So, are they true? Let's find out

Myth 1:

An object always moves in the direction of the net force exerted on it.

Materials: tennis ball, baseball bat, and Flip Video camera

Procedure:

1. Set up the video in an open area, power on the Flip Video camera and begin recording.

2. Throw the tennis straight up, let it bounce off the ground and begin to fall again.

3. Hit the tennis ball with the baseball bat in the way a batter would hit a baseball.

4. Upload the video to a computer.

5. Analyze the video and draw FBD's.

6. Using the video and the FBD's, decide whether the myth is busted or confirmed.

Prediction:

If an object always moves in the direction of the net force and we are hitting a tennis ball with a baseball bat, then immediately after the tennis ball leaves the bat, it show move towards the area between the bat and the ground, due to the net force of air resistance and free-fall pointing in that direction.

FBD:

Sum of the Forces:

Confirmed or Busted?

After the ball leaves the bat, it is moving in the opposite direction of the net force. Therefore, the myth is busted.

Myth 2:

An object always changes its motion if there s a force exerted on it by other objects.

Materials: 2 people, and a Flip Video camera

Procedure:

1. Set up in a fairly large area clear of obstacles, power on the Flip Video camera, and begin recording.

2. Set the two people around 15 ft apart facing each other.

3. Have one begin to sprint towards the other, trying to accelerate throughout the entire experiment.

4. The sprinting person will then sprint straight into the standing person, knocking him or her over.

5. The sprinting person will keep on trying to accelerate after they knock the standing person over.

6. Upload the video to a computer.

7. Analyze the video and draw a FBD of the sprinting person te momentwhen they hit the standing person.

8. Using the video and the FBD, determine whether the myth is busted or confirmed.

Prediction:

If an object always changes its motion when there is a force exerted on it by other objects and one person runs into another person, then the running person will change his or her motion, and change direction.

FBD:

Sum of the Forces:

Confirmed or Busted?

The sprinting person never changed direction. Therefore, the myth is busted.

Conclusion:

So obviously, these two myths are, in-fact, misconceptions. To someone not in the know about physics, they do seem true however. It is quite clear how these people may think so. They may think that forces instantly affect the direction of something and immediately reverse or alter its course. What force affect, however, is acceleration. An object will ACCELERATE in the direction of the net force. It is only when the acceleration brings the objects velocity to zero then will the object begin to move in the direction of the net force. Also, if an object maintains an acceleration throughout another force being exerted on it, it will not change its motion or direction. These myths are quite confusing. It is really easy to think them as true.

That Newton Guy was Right

Another unit passes behind me as I write. The unit was about Forces, however, we paid special attention to Newton's Laws, as one can see from the title. Again, I take a few moments to reflect upon what I learned easily, what took me awhile to learn, my strong problem solving skills, and my skills that need some improvement.

I found this unit to be fairly easy. One thing that especially help was the Free-Body-Diagrams. The "FBD's" helped make clear what forces were acting on the object and in which direction. Net force was also fairly easily, mainly because it is addition. Finding the individual forces was also easy. Newton's First Law was definitely the hardest Law to learn. It was the hardest because we had never done anything like it before. However, after a few problems is became as Mrs. Gende says, "Mickey-Mouse." Newton's First Law states that an object at rest tends to stay at rest, unless acted upon by another force, same as an object in constant motion. The law is all about translational equilibrium. The rule in the First law that the net force = 0 was the main concept. Very quickly, I was able to solve for any force in any axis. When we began to use trigonometry to solve for forces at an angle. I treated them as vectors, which is what they are. I did encounter a snag when the object and the axis were at an angle. Instead of changing the cosine to sine, and visa versa, I subtract theta from 90 and kept them the same. This ended up being the same as switching the sine and cosine, so it was not much of a problem. After I mastered the First Law, it was a breeze from there. We learned Newton's Third Law next, which states that every action has an equal and opposite reaction. That was the easiest law of the three. All we learned was to identify the reaction forces. Most reaction force phrases are the converses of the original force phrases, so they were easy from the start. The Second Law was also easy. The Second Law is about an object not in translational equilibrium, when the net force is not zero. One sets up the equation as the same as the First Law, except one replaces the "= 0" to "= ma," or equals mass times acceleration. This Law is very helpful when calculating apparent weight, the net force of an objects weight if the platform it is on is acceleration up or down. It is also very helpful when calculating different forces in pulley systems. Pulley systems usually have two or more FBD's, depending on how many objects there are. The Second Law can help you determine the direction of motion so you can tell which forces are positive and negative. The Second Law can even help when calculating friction. When there is friction, there is friction, the net force will almost never be zero. Also learning about mu was extremely interesting. It was a relief to learn that forces are that simple.

My problem solving skills were essentially did not change. I kept an open mind when looking for the way to solve the problem. This often helps me find ways to solve problems that others give up on. My ability to rework equations is still strong. I keep every option open. I have improved on staying focused on one part of the problem, although that could still be improved. I will start focusing on the next part and then lose my train of thought. I have begun to check the logic of my answer compared to the problem, but I could still check more. I have seen this many times when I would get the wrong answer then what is in the key and I would scan the problem over many times instead of looking at each individual part. My logical skills are strong, but taking the process and checking slowly are still being worked on.

I enjoyed this unit. Forces are awesome. The ability to understand our world, aka physics, is still awesome to me. I cannot wait to learn more.