Shadoof

Not that long ago I came up with a fun project idea when I was bored. I had some spare speakers laying around and felt like a fun thing to do would to add them to my current speaker system to help fill the room with sound better. To do this I drilled small holes in the back of my current computer speakers and then connected some wire in parallel, I then ran this wire through the ceiling and then soldered the leads to the speakers. By connecting them in parallel I reduced the resistance of the circuit but I also increased the current, thanks Ohms law! I thought this was all good, but then my dad brought up a good point, would the increase in current cause the amp in the speakers to blow. To my luck it seems like it all worked out fine as a few weeks later the speakers are working just as they were before. Another bit of physics that helped me in this project is magnetism. At the back of all speakers there is a sizable magnet used to vibrate the membrane and create the frequency of the music. I used this magnet as a form of mounting, I have ceiling tiles in this room so I just stuck the speakers to the ceiling where the metal was in the ceiling and I was done!

On a youtube channel that you may have all seen at one time or another they have made a video about throwing a soccer or football at somebody's face. This channel, called The Slow Mo Guys, records things in slow motion. In this video they show a face getting hit by a soccer ball in supper slow motion. The cool thing about this is that you can see the inertia that the head holds and its resistance to movement from the soccer ball. The other cool thing that you can see in super slow motion is that the energy the ball has goes from kinetic energy, as its moving, into potential energy, as the air inside is compressed as the ball is mushed against the head.

A mad scientist over on youtube has made a monstrosity of an instrument, it is made of 2 scanners, 8 hard drives, and 64 floppy drives.... 64... The reason for all of these strange electronic parts is so that the creator can play many different songs. Now how do you get these parts to sing the sweet sound of music. Well first off what is music, it is a bunch of frequencies all put together to create harmonies that sounds good to the ear. This is exactly what the flopotron is doing, each drive bay is set to a specific frequency and the program that he writes detects the frequency in the song and sends a command to the appropriate floppy drive to spin at that frequency. This is why there are so many floppy drives, so that songs can be faithfully recreated. While we covered what the floppy bays do, we have not covered the scanners or the hard drives, well the scanners operate on the same idea, except that they are mapped to the lower tones of the song as a scanner normally operates at a lower frequency than a floppy drive. The hard drives very simply act as the drums in the song, now as to how the creator managed to single out the drums in a song I don't know. My best idea is that if the program detects a a very sharp spike in amplitude then it will trigger a hard drive.

Love the show, its a brave feat trying to explain what happens in the show...

In most modern smartphones there is a feature called NFC, which is short for Near Field Communication. This tech uses electromagnetic induction with two loop antennas and the information is transferred on a radio signal in the 13.56 MHz band. If a device approaches another device this is called peer-to-peer sharing and both of the devices generate RF fields to transfer data. But in the case of a NFC tag, the tag does not have its own power supply, therefore it uses inductance from the active device and then transfers a RF signal. There are many applications for this technology that anybody with a phone can do. Currently anybody with a relatively new iPhone or Android can use NFC to wirelessly pay were it is available. But if you have an Android and some NFC tags around you can program them to carry out simple or complex functions. The tag pictured above, only about 3.5 cm2, has been programmed to give the wi-fi password to anybody that touches their phone to it. Down below you can see the inside of the tag thanks to it being thin.

Sounds fun, maybe I should wear my hat more often!

In the E&M course we learned that there can never be a mono pole of a magnet. We can tell this because of Gauss's law for B-field. But a company has found a way to print different poles on the same surface, they do this by printing what they call "maxels" onto the surface of a magnet. The different applications for these could be magnets that attract to a certain distance and then repel once closer together. They can also make "short-throw" magnets that are extremely strong but only attract a few centimeters from the surface of the magnet. It is hard to explain everything that these magnets and their designs can do so there is a video below about how they are made and what they do.

Eh, you aren't that experienced, you are good enough.

This sounds incredible.

Huh I didn't know that the paper on the outside would act as a wick, I always thought that the reason the wick didn't immediately burn on a normal candle is because it is surrounded, guess that is not the case.

Very interesting, I always find optical illusions cool.

The High School recently put on a musical production called The Addams Family, for stage crew we had to build the set which includes something called a fly system. On this production we had many parts of the set on the system in order to fly them in and out. For instance one of the bars held an entire wall that was used as a backdrop that would only let in small spots of light to resemble stars. This was moved often as the scene changed from inside to outside a lot. The way that the fly system works is a set of counter weights that offsets the weight of whatever is on the bar. As you can see above the weights are put on a platform that is connected to a long rope on a pulley system, however this pulley system is 1:1 so there is no mechanical advantage. Each weight weighs about 20 pounds, so on the large stack in the picture it is meant to lift something weighing around 320 pounds. The problem with trying to move something so heavy is that the bar is not going to want to move due to inertia as the mass of the system is double the mass of the object being lifted. Another problem that arises is that if we need to make a quick scene change then the fly needs to go up quickly. The big mass and the large speed give the system a lot of momentum that needs to be stopped carefully or else something may break.

I recently saw a video of an open MRI machine, I didn't know that there is one magnet that just spins really fast on the inside along with other equipment. It's amazing that it's perfectly balanced so it doesn't tear itself to pieces.

Another crazy creation from Boston Dynamics is the Sand Flea. This little robot has the ability to jump, very high. the 11 pound, or 4.99 kg robot has the ability to jump 30 feet in the air, or 9.14 meters. Using potential energy we can calculate the energy needed to launch the robot. Using mgh we can see that the robot outputs 446.96 Joules of energy for a full height launch. Also assuming that no energy is lost the launch velocity of the bot is about 13 m/s. Boston Dynamics say that the robot can launch about 25 times, giving the total energy within the robot to be about 11174 Joules or about 69837500000000000000000 eV.

Quite recently Boston Dynamics made another cool looking robot that is built with two legs and runs on wheels. In order for this robot to be able to move around without falling over. The ability to not fall over is helped by inertia and the very complex computers within the robot allowing for many calculations to be made in order to put the robots weight in exactly the right spot. What is the most surprising thing about this robot is it's ability to jump completely autonomously. It is able to detect an object in front of it and make the correct calculations to jump the object and safely land on the other side. The way the robot turns and stops also shows how inertia is used, as the robot is stopping it will lean back as to counter act the inertia wanting to send the top of the robot forward. Again as the robot is turning to either side, it leans the direction it wants to go in order to not tip over. Here is a short video demonstrating all of its sensibilities.

As we know through kinematics the period of a pendulum is determined by its length, by increasing the length of the pendulum the time it takes for one cycle gets a little longer. If we line up a bunch of pendulums in a row and just make each string a little longer than the last we can make a very cool looking pendulum wave. Eventually these pendulums will become out of sync and it will look like a mess, but they will follow a pattern and will eventually make the very satisfying wave form once again.

In old times, hunters didn't have guns and cool stuff to help get food. They had to come up with a new and genius way to hunt animals for delicious food. Around 21,000 years ago, some people in the modern day french area came up with the idea of using a lever arm to be able to throw a spear faster, farther, and more accurate. The way in which this device works is that it acts on a lever arm. Since the throwing arm is long more force is applied to the object, effectively multiplying the force put into the spear.

A fantastic game that has an incredible physics physics engine is Kerbal Space Program. At the end of Physics C we do get to play with this game, but I own the game and have had many fun times in it. The premise of the game is you own a space agency on the planet Kerbin (earth). You have to design rockets or planes that can power themselves taking into account of lift and mass of the aircraft. You also have to worry about how the atmosphere will effect the craft including the drag due to air resistance. The game also lets you do gravity assists around any planet, probably using the gravitational force formula. It is a fun game to just mess around in and see how many rockets you can strap to a single capsule. But it can also be very difficult because of the real world physics you have to deal with when trying to land a space craft on the Mun.

I think this actually happens on the international space station, just on a smaller scale. Pretty sure the name for it is Time Dilation.

A recent Youtube video from a channel called Vsauce caught my attention. In the video he mentions this line created by a specific set of geometric events. This line is quite special in its properties, if made into a 3D object it is the fastest path from one point to another. This is due to the perfect balance between distance traveled and velocity. In this video you can see the three different paths that are built, the linear path, the Brachistochrone path, and the 'extreme' path as they call it. The linear path has the least amount of distance traveled, but also at a slower rate then the others. The 'extreme' path has the greatest speed, but also the most distance to travel. And the Brachistochrone path has the perfect mix of speed and distance to travel making it the fastest. Another interesting property of the Brachistochrone curve is that no matter where the ball starts on the path it takes the exact same time to reach the bottom. Here is the link to the full video if you are interested in the geometry part of it too.

In this weeks episode (Episode 11) of The Grand Tour, a motoring show with the old presenters from Top Gear UK, there was a section in the show were physics played quite a big role in getting a shot right. In the shot they fired a car, assumed off of an air cannon, onto a boat. In order to do this somebody needed to calculate using kinematics how far the car would go given a supplied force. Taking what was shown in the show it is quite difficult to try and guess exactly how they did given there is too many unknown values. I can imagine that they also took some air resistance into the calculation as they landed the car almost directly on the boat. Lets try to find how far the boat is from where the car is launched. In the video the car seems to be launched from a fairly low angle, lets say 25°. I can also tell from the video that the time the car enters the frame to the time it comes in contact with the boat is close to 2.5 seconds, taking into account they didn't slow the footage down. With this time we can use the equation to find it's initial velocity using Vf=Voy+a(t/2). With this calculation we find that Vyo is 12.25 m/s. Using some trig we can find Vx=(12.25/tan(25)) which leaves us with a Vx of 26.27 m/s. Then using ΔX=Vot we can find that the distance the car has to travel is around 66.88m.

The liquid, solid, mixture I like the most is water and dry ice in a sealed container. Very nice explosion.

I remember the one lab we did were we made little speakers, it was fun yet difficult. It makes me appreciate what the engineers do to make proper speakers sound so good.

I saw something like this once, completely through a browser using OpenGL. It was quite impressive.

What's fun is you can enable different forms of 'colorblindness' on your phone to simulate the effect.