blog 7

Today I was EXTREMELY bored….so I was lying around thinking, WHAT ON EARTH SHOULD I DO MY PHYSICS BLOG ON? Well, while I was wandering around my house I found some little hand sanitizers with rubber cases around them so that you can attach them to your bag.  I decided to start spinning the sanitizers around in circles because I had nothing better to do.  To my amazement, I realized that I was witnessing circular motion right in front of my eyes!  In physics we learned that centripetal acceleration is equal to the velocity squared divided by radius.  Because the hand sanitizer holder thing has such a small radius, it probably has a very large linear acceleration.  Even if the sanitizer were travelling at constant velocity, it would be accelerating because it is changing direction.  We also learned that centripetal force is equal to the mass times the centripetal acceleration.  The sanitizer has a small mass so it definitely will not have as much centripetal force as a ball.  Yay for physics! J

blog 6

This weekend I went with my older brother and his family to the ‘Iolani v. Kaimuki state football game.  In physics we learned about impulse and momentum.  We learned that momentum equals mass times velocity.  When the football is thrown, it has a lot of momentum because it has a large velocity.  We also learned that impulse is equal to the change in momentum or force times time.  When receivers, such as Josiah, try to catch the ball, they try to have “soft hands” and increase the amount of time it takes to catch the ball so that they can reduce the amount of force exerted on them by the ball.  Also, when our awesome defense tackles the other team, they tend to have a larger momentum than the other players.  When this happens there is usually a stick collision and the defensive player will force the offensive player into the ground or in the other direction.  Go Raiders!

Blog 5

http://www.youtube.com/watch?v=BgonbR2TiWo (my video wouldn't upload...so I uploaded it to youtube...here's the link!)

Today at church, I was pondering my blog assignment and thinking, “Where on earth can I find something to do my physics blog on?”  Suddenly, a tall man went up to the pulpit to say a few words.  In order for the microphone to reach his mouth, the bishop had to raise the pulpit.  The machine that allows the pulpit to move, does WORK as it pushes the pulpit upwards a certain distance.  The amount of work done by the pulpit machine is equal to the force applied (which would be around the weight of the pulpit) times the distance the pulpit was raised.  After the tall man spoke, a shorter man went up to speak.  Since the pulpit was too high, the bishop once again had to move the pulpit down to its original position.  In physics we learn that net work is equal to force times displacement.  The net work performed by the pulpit machine after the bishop moved it back down would be zero because the displacement is zero (it returned to its original position).  It’s amazing that physics applies to church! J  (THIS VIDEO WAS NOT TAKEN DURING CHURCH, BUT ITS THE SAME PULPIT)

Blog 4

So, today I went to the Doris Duke Theatre to listen to the famous professional pianist, Anton Kuerti.  For his performance, Mr. Kuerti played on a Steinway Model D Grand Piano, borrowed from Edward Eu.  Now, you’re probably wondering how in the world does this relate to physics!?!?!

In physics we’re learning about friction and Newton’s Laws.  In order to get the piano to the Doris Duke Theatre, it had to be moved and pushed and pulled multiple times.  For instance, in order to move the piano to the center of the stage, the force exerted by the person pushing it must be greater than the force of friction opposing it.  Considering that grand piano’s have a HUGE mass, the normal force of the piano would also be great.  From physics, we know that friction=(miu)(normal force).  Therefore, we know that there is a lot of friction to keep the piano from moving.

Physics really is EVERYWHERE!

Blog 3

In physics we are learning about Newton's laws.  Newton's second law states that, net force=mass * acceleration.  When an object is at equlibrium, there is no acceleration, and the net force is zero.  This is the chandelier that hangs above my dinner table.  The chandelier is at equilibrium because it is at a state of no change.  Also, it is not accelerating in either direction.  The reason the chandelier is not moving is because there is a chain holding it to the ceiling.  The pulling force of the chain is known as tension.  In order for the chandelier to be at rest, the y component of the tension (of the chain) must be equal to the weight of the chandelier, so that the y components will cancel out to zero.  I'm very glad that the chain has enough tension (net force) to hold up the chandelier!  If it didn't, we wouldn't have a dinner table, or light to see!

Blog 2

In physics we're starting to learn about projectile motion.  Projectile motion is parabolic due to the force of gravity.  At first, I had the hardest time thinking of where to find an example of a parabola, when in reality, parabolas are everywhere!  I found the perfect example of a parabola at my own house.  This is a picture of the water fountain in front of my house, which forms a parabola when you turn it on.  If there wasn't such thing as gravity, the water  would've continued to rise higher and higher and never come back down.  Luckily, it did, and I got to drink some water.   If I were to place a hose at the exact same height as the water fountain, facing downward, both the fountain and the hose water would reach the ground at the same time.  This is because gravity only affects vertical velocity, not horizontal, so the water is accelerating towards the ground at the same rate.

Today I drove from home to church and back home.  From the moment I backed out of my garage, I was accelerating.  I had a low velocity because I didn't want to hit anything around me as I was in reverse.  When I drove in the residential areas I remained at a velocity of +25 mph, but when I reached Kamehameha Highway, I accelerated to reach 35 mph.  Of course, since I'm just beginning to drive, I did not accelerate at a constant rate because I kept jerking.  Each time I came to a stop sign or stop light, I gradually accelerated negatively until I came to a complete stop at the stop line.  Also, whenever I reached a turn I had to step on the brake and lower my velocity so I could remain in control of the car and turn safely.  After church was over, I drove back home and pulled into my garage.  At that point, my displacement was zero.