The Physics of Chewy Bars

Okay, maybe not exactly the Physics that goes into Chewy Bars, or the Physics that Chewy Bars perform (if any...), but Physics that I noticed carrying a box of Chewy Bars to Cross Country practice on Friday. I didn't feel like carrying the box under my arm, or infront of me, so I decided to hold on to the top of the box instead. As I was walking along and noticing that my hand was starting to hurt, I thought, "Hey! The only thing keeping the box from slipping out of my hand is....(drumroll, please...) Static Friction!" The maximum static friction force between the box and my squeezing fingers must have been greater than the force needed to keep the box in the air and my hand, otherwise it would have slipped out of my grip. And let me tell you, holding that box was not easy (see my hand straining? Sorry, the picture's a little dark). I could even feel the box sticking to my fingers, with the weight of the box pulling down on my skin. Don't worry, it was nowhere near as creepy as it sounds.

Also, when I lift the box (with my hand in the same place), I do work! I'm moving a mass in the y direction, so my work would be F(delta)y, or mg(delta)y, if I am moving the box at a constant velocity. I am also increasing the potential energy by situating the box at a higher position from the Earth. The PE of the box at any given point would be mgy.

This experience shows that Physics is truly present everywhere, all the time. Who would have thought that I would encounter Physics doing something as simple as holding a box of Chewy Bars? Well, I also realized another thing; if I want to do less work lifting the box, then I have to decrease its mass, decreasing its weight and the force needed to move the box. Oh well, I guess I'll just have to eat one! :-)

Eurus, Notus, and Africanus

Hello fellow Physics students! I bet most of you are wondering, "What in the world is with this title?" But I hope my fellow AP Latin students are wondering, "Why is she reffering to the 'savage winds' that we recently read about in The Aeneid?" Well, I actually have a very interesting reason.
On Saturday, September 22, I attended the Iolani Cross Country Meet at Ford Island, and anyone who was there can testify to the fact that the wind was CRAZY!!!!! Dirt was flying everywhere, and the pop-up tents that housed the girls team were beginning to fly away! As I quickly ran to give my friend a hand in holding one of the tents from collapsing and/or blowing away, I realized, "Hey, there are forces at work here!" Before we began holding the tents against the wind, the wind was providing an x force that was greater than any opposing x forces, causing a strong net force that was threatening to send our tents flying through the air. But the moment one of us (or me in my bad diagram, I was in no position to take a picture even if I had a camera with me at the time) began to pull or push on the tent in the opposite direction to the wind, we evened out the x forces, resulting in a net x force of zero. I have included the Free Body Diagram for the simple forces working on the tent, even though I'm sure there are many more that I'm not aware of, perhaps ones like the wind making its way inside and pushing up on the tent, or othe people pulling on it. For that moment, I was glad the wind was not stronger than it was, but later, as I tried to lean into the wind to see if it would hold me up on its own, I woefully discovered that my weight, applied in the x direction (leaning into the wind) was greater than the force of the wind on my body, causing me to fall flat on my face had I not given up before that point. :-( Oh well. Oh yeah, and about "Eurus, Notus, and Africanus." Those were three of the "savage winds" that, when released, would rip up the earth and sea and send them flying through the sky. I think this was the kind of wind that Vergil was talking about. :-)

Friction, Forces, and Football

Let's see, Physics common in my life... You would not believe that I only just noticed a common example of friction as I was sitting at my computer, doing my Physics homework today. I was sitting in my rolling chair, and I realized "Hey! This chair has forces written all over it!" Not only does its weight, and therefore the normal force exerted by the floor, increase when I sit down on it, but the wheels have massive amounts of friction, and not just from the floor they roll on; the wheels have not exactly been lubricated anytime recently, so the wheel and axle create friction as well! I had never thought about it before. And, according to Newton's second law, the horizontal forces, mainly friction, are the reason that my horizontal push away from my desk does not make the chair travel very far! And then there are the forces that stop the chair quickly, such as the shoes and slippers that live about four feet behind my chair. :-) I feel sorry for them. Oh yeah, and in case you were wondering, that's my stuffed dog. His name is Taffy.
I really noticed a lot of physics this weekend. First on Friday night, I went to the football game at Aloha Stadium as part of the Marching Band, and I vividly noticed the travel pattern of the footbal on kickoffs (emphasized by the traditional trombone gliss following the ball), which was a parabola, as well as the velocity, both x and y. And then there was the Aloha Week Parade on Saturday morning, where I noticed that the normal force of the road on my body seems much increased when I'm marching on my toes, as they quickly started to hurt when I did, with the decreased surface area and all. As a result, my calf muscles are very stiff and sore right now. Oh, well, I'm used to it.

the first few weeks

whew! we've survived the first few weeks, the first test, and three quizzes in AP Physics! First 1D Kinematics, now 2! At first I thought 1D was going to be hard, but now I miss it. 2D has so much to think about! x position, y position, x velocity, y velocity, just velocity, initial velocity, AAAAAAAHHH! my brain is spinning. I keep feeling like I don't have enough information, but I'm sure I do, I'm just not sure what to do with it. Oh well, just have to keep practicing. It's fun though. I'm already seeing physics in daily life. Last year I heard one of my friends from Band say that the only way she got through the beginning of physics was football. I'm going to try her strategy and apply physics to my observations of the football game this Friday. This should be fun!!! :-)