Sunday, December 9, 2007

Sound



Guitars may be played acoustically, where the tone is produced by vibration of the strings and modulated by the hollow body, or they may rely on an amplifier that can electronically manipulate tone. The above clip is an example of the electric guitar being played by Tom Morello who has a distinct way of playing with multiple effects. Although it must seem like he has a dozen different pedals to make all these sounds that should be coming from a synthesizer he uses only a wah, whammy, and delay. The killswitch is important too to cut off sounds. He makes the guitar sound like anything but a guitar at some times.

I learned a bunch of other things about the guitar. And about my violin as well. Such as the bridge, to me it seemed somewhat useless. But instead the main purpose of the bridge on a guitar or violin is to transfer the vibration from the strings to the soundboard, which vibrates the air inside of the instrument, thereby amplifying the sound produced by the strings. Well thats pretty important.

Oftentimes i wish i had an electric violin to play around with the various effects. If i did i would have a violin without much of a body. It would have pickups however. Pickups are attached to a guitar/violin that detect (or "pick up") string vibrations and convert the mechanical energy of the string into electrical energy. The resultant electrical signal can then be electronically amplified. And in regards to the whammy bar, it allows me to modulate the pitch moving the bridge up and down.

Very interesting chapter on sound. Especially since its such an inescapable part of our lives. Yet, such an enjoyable part.

Sunday, December 2, 2007

Excuse me while I kiss the sky!



Yes. Hey Joe! I love how Hendrix plays his strat upside down because he's a lefty. His strings even sound different too.

I can't wait for chapter 17 on sound. I couldn't bear rehash the simple harmonic motion that we just covered. I guess all i've got to remember is the usage of conservation of E total. Actually, we've to rememeber everything we've covered right?

Next week ill try to attempt explain different techniques and stuff using physics. Fun fun :) In the meantime however, im sick.

Sunday, November 25, 2007

Bungee Jumping!



So that's a short on bungee jumping at the original bungee jumping site in Queenstown, New Zealand with an introduction by a bungee company.

If the spring action on the bungee cord wasn't dampened then this would be an example of simple harmonic motion. However, no one would be able to stop, so that wouldn't be good for advertising. The motion is periodic, as it repeats itself with intervals in a specific manner; it is described as being sinusoidal, with constant amplitude. A motion with frequency f has period = 1/f. Thus if there was a period of 4 seconds the frequency would be 0.25 hertz.

Okay well that's it from me. I'm going to enjoy the rest of my thanksgiving break. There really is so much I have to be thankful for and I should be thankful year round.

Monday, November 19, 2007

The Challenger Deep


My homepage for Safari is a random page on wikipedia. I'll say that 40% I find a useless irrelevant page like one on some unknown district in India or in Minnesota. However, the other times I can find true gems and oddities (Vang Stone or Australian Senate election of 1967). This time though I found something that correlates with my work in physics and fluid motion.

The Mariana Trench is the worlds deepest oceanic trench. It goes down to a maximum 11 km down. This makes it the deepest location on the surface of the earth's crust. It is located where the Pacific plate is subducted beneath the Philippine plate. In 1960 the bathyscape(similar to a spherical shape so as not to be crushed by the intense pressure) "Trieste" reached the bottom with two men. The gauge presure of the seawater at the bottom is 1030kg/mcubed times 9.8m/s squared times 11000m. This is equal to 111034000 Pascals. This is over a thousand times greater than the atmospheric pressure we experience at sea level! It is almost scary to imagine the sheer darkness and fear one would experince being at that depth, although life persists even at that depth (foot long flounders and shrimp).

So now I've gone from space to the depths of the ocean. Hauntingly but beautifully, physics is omnipresent.

Saturday, November 10, 2007

Eleven Flights More :(


Mission STS-120 was a space shuttle mission (Discovery) to the ISS that was launched on October 23 and landed this Wednesday the 7th. Sadly however, I was reminded that only eleven more missions will be flown by the space shuttle program until its decommissioning in 2010. On a better note the ISS is one more module closer to completion as the Harmony module (a US module built in Italy as part of a joint ESA-NASA deal) was attached; it is a habitat module, and repairs were also performed.

The ecape velocity needed was 11200 m/s this escape velocity does not depend on the mass of the space shuttle although it may require more or less energy depending on the payload of the space shuttle. The space shuttle escaped earth gravity to enter into a LEO or low earth orbit to meet with the ISS at about 320 km above the earths surface. The value of g at this height is GM over (r + 320km)squared. However, since this is at such a low (comparatively) orbit the value of g here is nearly the same as on the surface. The weightlessness is caused by the effects of freefall.

Sunday, November 4, 2007



Heres a video that made me wonder what the initial angular acceleration of the system with the Tundra truck would be if my family's four door sedan was placed on the other side of the seesaw. Assuming the whole seesaw is 70m long then the Tundra truck would be at 25m from the fulcrum while on the otherside my family car would be 35m away from the fulcrum on the right side of the seesaw. The video states the truck is 10000 pounds (4535.9 kg) while my car is probably around 4000 pounds (1814.3 kg) and the mass of the seesaw is probably 10000 pounds (4535.9 kg).

First, inertia of the system would be needed. I = (truck)mr^2 + (car)mr^2 + IS
By substituting values for the variables and I of the seesaw is 1/2ML^2 one finds that the system's moment of inertia is equal to 6909614.2 kg*m^2.

Now net torque is found by adding the torques of the car and the truck. Which is 488990 N*m.

Σt = iα and so angular acceleration is 0.0708 rad/s^squared. Its kinda slow but it makes sense when dealing with large masses that are nearly equidistance from the fulcrum.

In the video it is clear the initial angular acceleration is much larger when only the truck is on the seesaw at a great distance from the fulcrum.

Saturday, October 27, 2007

Fly Gundam!


I was watching an episode of 0080: war in the pocket. I noticed the space colonies were rotating. The different sections had different rotational speeds.

With further research I found out that many of these colonies are called O'Neill cylinders. One the first designs was "island one" a sphere with a diameter of 1.609km (804.5m). So to find the velocity at which the colony would have to rotate is using F= m(vsquared/r) to get 88.8 m/s. Another design calls for a cylinder rotating in different sections at different speeds. There is even an outer ring that rotates at various speeds for farming. In Gundam, the cylinders probably rotate way faster than 88.8 m/s since the rotation is too fast (for visual effect). Interestingly, in Rendezvous with Rama the object being explored also seems to be an O'Neill cylinder except without the mirrors and windows (needed for light).

These cylinders would need to be placed at Lagrange points. These points would allow a colony (only affected by gravity) to remain stationary between two objects, say the moon and earth. <> wikipedia includes some ways to calculate the five Lagrange points. This is demonstrative of center of mass, it being essential. However this is no longer a uniform circular movement since the objects take elliptical paths.

A large problem that confronts space exploration is the effect that radiation in space will have on colonists/explorers. At the scale of the O'Neill cylinder however, the air and the steel (perhaps another metal) hull will be sufficient protection.

Personally I can't wait for space colonies.. there's just something so enticing about space.

Sunday, October 21, 2007

Conservation of Momentum

Admittedly this video isn't that cool. By the way, I hope the other embedded video works now.



However, this is an example of (variation upon) newton's cradle. It's better than showing you the one on my desk. Here, momentum is conserved. When one ball is pulled back and allowed to hit the stationary balls the momentum is transfered to the ball on the opposite side and it moves. Here the balls (of same size and mass, and same plane of movement) are involved in an elastic collision. The KE is not changed to anything else. I also see this concept in the bowling ball return. When there is a line of bowling balls and a ball comes back and hits the series of balls only the last ball moves away. So anyways, happy rest of weekend everyone.

Sunday, October 14, 2007

Joon Lee!


The other day the car I was ridiing in got hit by another car. Although Hawaii state law is handy with its "no fault" clause it was obviously the other drivers fault. Turning onto a one lane street and signalling, the other driver (Joon Lee) sped up to pass and crashed into the front right of the car.

Now the car door hardly opens, however, I feel pity for the other car which seemed to sustain even more cosmetic damage. Fortunately nobody was hurt although my neck felt a little stiff.
I feel what helped reduce the effects of the minor collision were the "crumple zones" on the car. Although the impulse of the collision is the same, it increased the duration it took the other car to have the collision and thus reduced the average force. Thank goodness for that. Happy rest of weekend everyone!

Sunday, October 7, 2007

Rube Goldberg FTW!

I'll have to say that Rube Goldberg contraptions are awesome.

In what is basically an interactive physics program, Garry's Mod, one can simulate different physics (gravity, even static and kinetic friction) but heck, to put it bluntly, nobody talks about Gmod in those terms very often. But! when you're messing around with Rube Goldberg contraptions very minute differences can make something go amiss.

So here's a video that I really like. Everywhere there are examples of physics. I like the part at the end where the crates slide down a massive ramp. The people at the end are encountered by a massive load of kinetic energy because satrting from higher up means more potential energy and we all know for conservation PE + KE = KE +PE, although I wonder if the creator had to reduce some friction on the ramp. Well anyways, this is some fun fun stuff (to me at least :p). The only limit is imagination! (ha what a hackneyed phrase)


Sunday, September 30, 2007

Get a New Car


It seems everyone is having car problems as of late. Goodness knows why... Both of my family's cars have needed repairs and two of my friends have also had car problems. I'm starting to suspect that the repair places don't the greatest jobs either. Oh well.
On to the physical part! Going over on the H3 yesterday (I rarely go on H3 actually) I saw something that caught my eye. An old rickety brown car from what seemed to me was the 70s was really close to another car. Since we were going roughly 70 mph (112 kph) I thought, "whoa". As we started to pass the pair on left lane I realized the two were attached by a thick gnarled rope. And no, I didn't think about a picture unfortunately so the picture I do have doesn't explain the hilarious/interesting side to what I witnessed.
The rope wasn't at any angle so I figured why not calculate some work? If the car ahead was pulling the other car with a force of 15000 Newtons then over 1km 15million joules of work were needed. And I'm sure the distance was much much longer.
I'm glad that guy got someone to pull his car because a lot of work is involved. Not to mention the change in angle because of hills and the friction on the tires. And now imagine what life would be like without cars... It'd be like Virginia in 1732, rivers and poor roads (hah I'm writing a paper on Washington's formative years).
Happy rest of weekend again! Happy next week too everyone!

Sunday, September 23, 2007

Post Two!


Mid quarter has just passed! I'm that much closer to the end of year :) yet... I'm enjoying it all right now. For those who took Asian Studies last year, one has to enjoy the journey!
I moved my television from one floor to the other. It wasn't particularly easy work either. Sitting on its stand I first had to slide it off (with my brother's help of course, who am I, the Hulk?) and I overcame static friction to get the TV off the stand and hanging in the air. I estimate that the TV is about 70 pounds, which is roughly 32 kilograms. So thats about 314 Newtons of weight downward I was fighting with. If I had slid the TV along either the carpet or wood floor the coefficient of friction would have differed, if there was no friction then i could have pretty easily dragged the TV nearly anywhere (although stairs are different, that thing is an awkward object to move).
Well hopefully next weeks entry isnt so mundane :p oh well happy rest of weekend all!

Sunday, September 16, 2007

Wait, hold on... cue the elevator music



Hey everyone, Happy weekend! If physics were an elevator... it'd be 88 floors in reach and some little kid just pushed every button. Good thing I have my laptop though! I can thankfully still access my physics book.
So elevators. Something as mudane and as simple as an elevator still has so many physical principles. That's something I appreciate about Physics; it, more than the other sciences is right there in front of your eyes.
Now I'll never ride an elevator the same way again. So there are essentially three situations when one is in an elevator: zero acceleration (when speed is constant or the elevator car is at rest), upward acceleration, and downward acceleration. At zero acceleration the opposing forces (Fnormal and Fgravity) balance each other out and the rider (me I suppose) feels no change in my weight.
During upward acceleration however, the normal force is greater the force of gravity (which doesn't change) and one feels heavier. The opposite is true for downward acceleration when the normal force is less than gravity and one feels lighter. The same principle using the equation from Newton's second law applies to other "weightless" situations like roller coasters.
Which brings me to why there isn't a theme park here in Hawaii? Every physics student would have to go on it!
Now I got to do better on quizzes! Short term Sean goal! Physics FTW! Kikaida!

Saturday, September 8, 2007

Post Number One!

I look forward to a wholesome year of physics! I'm gonna break down problems into little acorns and so bit by bit solve them like a squirrel saves each acorn for the long winter. There is nothing to fear but fear itself!