[The Third Blog] Force.

       This afternoon, as a break from homework, I decided to clean my room.  After folding my clothes and putting some things away, I was in the mood to rearrange the little bit of furniture that I have...yet again. My room is the smallest in our house (why, I ask?), so I'm always trying to find an arrangement that uses the space I have most effectively.  As I was moving things around, I realized that physics could be applied to what I was doing. Amongst other things, my little Sunday afternoon project demonstrated Newton's third law of motion - for every action, there is an equal and opposite reaction: as I pushed forward against my bed to move it, it was also pushing back against me with the same force. Thanks to physics, I was also aware of the specific forces that were acting on my bed throughout the process. When at rest, the bed experienced forces of gravity & normal force (which counteract each other) as well as static friction. As I began to push on the bed, though, while gravity and normal force were still being applied, the force of my push was also added, and static friction became kinetic friction, which worked against my applied force. I also learned that the force of static friction is greater than that of kinetic friction, which is why it was harder to get my bed to move initially than it was to keep it moving. Well, without further ado, here is the result of my physics-filled project (not very exciting, I know, but that's okay.):

I should have done a before/after type of thing, but that thought didn't
really occur to me until everything was moved - whoops.

[The Second Blog] Projectiles.

     This week, we extended our knowledge of position, velocity, and acceleration into two (and even three) dimensions with the lesson on projectiles.  A projectile is an object projected, for lack of a better word, into space that, once released, is only influenced by the force of gravity. The motion of a projectile can be seen as my brother shoots a basketball. Today he just so happened to be doing so—in the living room (but at least he didn’t hit anything).  I don’t generally pay attention to him when he’s practicing – he wouldn’t want me to, anyway – but since I could relate it to our physics concepts, I decided to observe for a second.

[General graphs depicting
projectile motion]

     Being that it is a projectile, when the basketball is shot into the air, it moves in a parabolic path. This is due to the fact that the only force acting on the ball, assuming no air resistance, is gravity. Therefore, in the y-dimension, because of the acceleration of gravity – a constant –9.8 m/s² – acting on the ball, position follows a curved path, increasing initially then decreasing to form the shape of a parabola, with velocity decreasing (in the positive direction) from the time the ball is released until the time that it reaches the peak of its trajectory and increasing (but in the negative direction) on its way back down after reaching the peak. In the x-dimension, though, because there are no forces, position increases at a constant rate, velocity remains constant, and thus acceleration is zero. 

   

[The First Blog] Kinematics.

       Yesterday, as I took a break from taking history notes, I stopped to think about what to write for this blog (yes, simple as this first concept may seem, I had to think about it). But nonetheless, I eventually got somewhere. I knew that I would be attending the UH versus UCLA volleyball match in the evening, so as a newly "physics-literate" person, I began thinking about the movement of the ball - and the physics behind it - as it makes its way around the court. I tried to focus on applying physics during a serve because that seemed easiest to capture in a picture, but after several failed attempts, I concluded that I am not a good photographer, and hopefully my application of physics proves more successful. So here it goes:
       As the ball is tossed into the air, even though it is moving in the positive direction, it experiences decreasing velocity because the force of gravity, -9.8 m/s², is pulling it down. When it reaches the top of its trajectory, the ball has a velocity of 0.0 m/s before it begins to make its way back toward the earth. As it comes back down, the ball’s speed increases at the same rate at which it was decreasing on its way up (since acceleration, which is gravity in this case, remains constant).  However, even though speed is increasing, the direction in which the ball is traveling is negative, and thus, since velocity is a vector, the ball is still experiencing decreasing velocity. [Yay! The first blog -- completed. :)]