The Physics of Bullying

A friend recently gave me a heads up that they found a picture of me online. Unfortunately, when I went to investigate, all I found was an embarrassing picture of me being punched. By Richard Chang, no less~~ (shame!). I never wanted my brief incidence of e-fame to be so violent!




I fondly remember this incident where his fist navigated squarely to my stomach. While wallowing in pain, I immediately saw the PHYSICS of my misfortune:

Impulse is defined as the change in momentum. Assuming that Richard's fist has a mass of .5 kg, an initial velocity of 5 m/s and a final velocity of 0 m/s, I calculated the change in momentum of Richard's fist. Note that final momentum is zero due to final velocity being zero, so change in momentum is simply equal to (negative) initial momentum.

mv = (.5)(5)=2.5 kg x m / s

0 kg m/s - 2.5 kg m /s = -2.5 m/s

Another variable we've used many times is the quotient of impulse and time, average force. Given the time of contact, say, 0.3 seconds, I can calculate exactly how pissed off Richard was (how much force he used in his punch).

F(average) = changeMomentum (Impulse)/changeTime

F(average)=-2.5/0.3 ~ -8.33 Newtons

Since Force is a vector, it has consequently magnitude and direction. Richard's fist can have a negative component along a coordinate axis, but having a negative magnitude makes no sense. Therefore, Richard's force was approximately 8 (positive) Newtons.

On a different note, I was asked to exclude John McCain from any future blogs. Sorry.

Facebooks

This week, a friend of mine sent me a pretty entertaining image via Facebook. Although Facebook is notorious for having the credibility of a fresh Wikipedia article, I recognized that the image was actually quite relevant to Physics:



One more thing; could the man in the image above, be related to our Republican hero here?




Jokes aside, I've finally caught up with the reading since missing a day due to a random cold. Momentum is a vector equal to mass times velocity, going in the same direction as velocity. As derived from Newton's laws, in a system with no outside forces (barring friction and air resistance), the momentum in a system remains constant. In our everyday lives, momentum is transferred quickly; in the collision of two objects, one will usually decelerate (or stop), and the other will usually accelerate. A common term today is the "domino effect," a "chain reaction" which occurs when a small change causes a similar change nearby, which then will cause another similar change." Most likely, this refers to a system of dominoes, in which as the first domino falls, the momentum from the fall transfers to each successive domino until the last domino, perhaps quite far away ultimately falls too

Now I don't have dominoes, but my mom's collection of Chinese dictionaries should suffice:





An interesting thing to note is that while momentum of the system supposedly should remain constant, certain books in the video clip appear to fall more quickly than others. The reason is that each book is its own system with different masses. Unlike dominoes which have uniform masses and should consequently should all fall at a uniform rate, the masses of my mom's dictionaries are different. If momentum is the product of mass times velocity, different masses should result in different momenta. The overall momentum of the system still obeys the law of conservation of momentum, however.

Being the conscientious scientist I am, I remembered to wear my safety goggles before performing any potentially harmful experiment (as always). Mocking me is completely unnecessary, Teresa.

Childhood Punishment: Experience is the Best Teacher

At some point in my life, I entertained the notion of becoming a photographer. Indeed, it seemed a pretty simple task without the boring office work and the inelastic nine-to-five rut: five days a week, twenty one a month.

If this class has taught me anything yet, I've learned to abort said "goal in life." Taking pictures isn't so bad; the difficult part seems to be not randomly including half of someone's face (sorry Mark).

For the purposes of this week, carefully examine the classy wine glasses that I managed to include. First, they appear to be stationary and unmoving. In addition, they appear to be made of glass. Also, they have pretty cool napkins that look carefully folded and intricately positioned.

Recall from childhood what happens when glass is dropped on the ground--it breaks immediately, emitting a sound of high, shattering frequency. If your parents were around, oh boy. You'd learn quickly to be more careful, or in my case, break the glass when my parents weren't around instead. Experientia docet, my friends: "Experience is the best teacher" :]

Recall additionally from Chemistry that according to the First Law of Thermodynamics, energy can not be created nor destroyed. SO, what exactly happens then, when the glass falls, and breaks, and impending punishment awaits? To make a long story short, an object not in motion is not necessarily void of energy. Energy is classified further into stored "potential energy" and mobile "kinetic energy". When the glasses rest on a table, all their energy is "potential"; they don't actually move or fall or break. If the glasses do indeed fal, their energy is "kinetic," the energy of motion. Energy is not being created out of nowhere, but instead being transformed from potential into kinetic in an intricate process.


In hindsight, the solution to avoiding childhood punishment is to prevent potential energy from becoming kinetic energy. How can that be done?
Try it yourself:


Experientia docet--Experience is the best teacher.

Can we break a rule??? please??????

Three day weekends are awesome. Totally. I had fun even though I slept through a good portion of it.

In celebration, here's a penguin:




The downside to my happily restful, relaxed weekend is that it's over already. And here I am struggling through work on a Sunday night, just like every other Sunday night this year. It's too bad that one of my New Years' resolutions was to be less predictable.

For whatever reason, most likely the deficiencies of the English language, a physicist's definition of work is very different from my 'work' that i struggle through on a given Sunday night. After googling the etymology of the word "work", I got the following results:

'Work : Middle English, from Old English weorc; see werg- in Indo-European roots'

Moving to the status quo of our Physics world, we stumble upon 'work' as a word that has a meaning very different from the everyday interpretation of it. Recall that last week, I pointed out the failures of the Latin language. Research now shows English failed all by itself.

Since I've lost faith in the linguistic arts already, let's dissect the physicist's definition of work. In simplest terms, work is defined as force times distance. The ambiguous part is the distance portion of work; in order for work to be accomplished, the object doing work must go some distance (specifically horizontal distance). If the object moves a distance of zero, then no work is accomplished (force times zero would mean work is also zero).

With that in mind, I present two examples of work (or no work!), again using the physicist's definition:


Exhibit A: Work or no work?


Here, we have Thanh Vu ever-so-slightly gesturing David Martorana towards the Colonel. Now, the force that Truong exerts on David is both minimal and negligible, however it is not zero-- which means that if David moved ever-so-slightly at all, then work is being accomplished.

Now I don't recall the exact context, but David has on the infamous "can we break a rule??? please??????" expression.

SOOOO EZ.


Exhibit B: Work or no work?


It takes strenuous effort (force!) to maintain such gestures. However in this case, everyone is smiling for the camera and firmly rooted in place; more importantly, nobody is moving. Hence, distance traveled is zero, and no work is accomplished.

Such a pity too; Rayfe looks like he was trying pretty hard =[.



I'm not sure which definition of work I'm more comfortable with. I think it depends on whether David got to break his rule or not.