#14

This week we learned a lot about waves and there are waves all over the world. Not only speed waves, we encounter so many waves in our daily lives. For example, while i was microwaving, i thought about waves because its in fact microWAVE. As waves go through the food, it moves the particles and that makes the food warm up (isnt that right, doc?). We also use waves to transmit the radiowaves and so on. But those are all invisible waves so we dont really notice them around. We notice more of ocean waves and stuff. Waves at the beach is the most commonly known example of a wave. We like to go surf and bodyboard when theres a high amplitude. However, when it has high amplitudes and higher frequency, it is dangerous. If you arent good at swimming like i am and go beach on those days, you have made a fatal error. Waves are fearlful though depending on what kind, it is quite useful. some light waves are pretty dangerous too. Some of them can cause skin cancer. Waves are seriouslly all over the world without any exceptions. Its important to learn stuff like that, right doc?

#13

While i was spinning my pen around (because i was bored while filing out informations for my college apps), i noticed that there was a spring inside a pen (i knew it existed but i didnt really care back then). As i observed that spring, i began to learn the mechanics of it. I was impressed how clever they made that thing. As i was impressed, and before i even knew it, i started to wonder if i can figure out the spring constants and some mechanics that actually enables the pen to work. i designed a experiment just like the lab. Except i didnt have the exact weight for 5g~100g objects, i couldnt really do the same thing as a lab. As a matter of fact, i ruined a spring by putting too much weight on it. It was great how i couldnt really just that pen anymore but its alright because i actually was thinking about physics while i was playing around.

#12

This weekend was pretty awesome since it was four day weekend and there was barely any homework. It was pretty nice getting rest from everything once in a while. Therefore, i didnt really have anything physics related this weekend cuz i pretty much spent all my day at home just sitting around, doing nothing. But on saturday, i went out with my friends again to bryans (doc, you gotta come with us!). But since i already talked about physics of pool, im not going to. I actually want to talk about centripetal force and centrifugal force. while we were driving around, people in regular physics didnt know the difference between centrifugal and centripetal force. some of them even argued theyre the same thing. So i told them that centripetal force is the net force and centrifugal is the imaginary force that you feel. When we got to the curve, i told them there is radially inward acceleration and they nodded. And when everyone started to feel the push towards outside, i yelled "THIS IS CENTRIFUGAL FORCE!"
that was fun

#11

This weekend, i watched couple tv shows that dealt with water. One of them was mythbusters and what they were trying to do was to examine if all those ninja skills were actually possible in real life. They tried walking on water by using wooden panels. The point of that is to increase the volume and area of the object touching water proportional to the mass so it would have higher FB's. It sounds very reasonable and it sounds like it works using the wooden slippers because woods has not that much of a mass but can provide a good volume. However, the plan totally failed because the mass of a human being was too much for that FB created by wooden panels. Perhaps if it had a greater volume then maybe it could work out. So they used styrofoam and made a big shoes out of it. The volume of that shoes was apporoximately .9m cubed or something close to it. Im not sure the exact value but from my estimate, thats the volume. So the guy had totaly of 1.8m cubed as a volume for 2 shoes. And the plan was a success because the volume provided more FB force than the weight.

Physics Journal #10

Today, as i was watching the show Man vs Wild, the idea of using sun as a way to know the direction came across quite often. As i was watching and listening to the logic of that, i remembered that although it looks like sun is moving, its actually the earth that is rotating around the sun. Also, i remembered that earth rotates on its axis once every 24 hours. All of these informations reminded me of the lab we did. As i remembered the lab, i remembered that because theres a satellite in the outer space orbitting around at the same speed as the earth rotates.
Also, in man vs wild, there was a part when he slipped down the ice to move through the places to walk. The friction coefficient must have been very low (both static and kinetic) because he slipped down easily and quickly. I even thought that if we tried to find the speed he was sliding down, we could have just ommitted the friction force/work out of the system. Since i doubt the acceleration was constant, i would choose to use cons. of energy concept to find out his velocity, if i ever do.

Physics Journal #9

this weekend, we xc runners and supporters went to maui to compete in states championship. As a team we ran through the course and coaches made checkpoints about how to attack the course. While we were going through that, one thing caught my attention. When our coach told us to let the gravity do the work goin down the hill, i thought to myself, hey we learned this in physics. So with an intelligent mind of mine (yes you can laugh, doc), i yelled out, "guys, use the mg sin theta!" people in physics understood and laughed and people who didnt take physics needed an explanation so we all explained to the freshmen what we were referring to. we explained to them that the weight is mg and because it was an inclined plane, the net force is going downward parallelly along the surface of the inclined plane. therefore we use the mg sin(theta). Which means, on the other hand, when the runners were running upward, they were fighting back the force, mg sin (theta). Though it is one of the simplest physics we learned so far, it was good to review these kind of stuff.

physics journal #8

this weekend i experienced the centripetal acceleration. I was inside a car with my friend and we made a turn on one of the intersection. As we turned the corner, i thought about the ideas of centripetal acceleration and started explaining it to my friend. I told him that because we were going at 40 mph on the straight and made a turn with a constant velocity, and with the radius of the intersection curve being about 10m or so, we can calculate the centripetal acceleration. i simply converted 40mph into kmph, which is 40mph*1.6km/mile = 64km/h. Now i could apply that velocity-squared/radius equation and solved for the acceleration, which was approximately 409.6km/hr^2. when i told this fact to my friend who was driving, he was impressed in how fast we were accelerating towards center as we turned. I also explained to him about how important free-body diagram was when dealing with inclined plane problems. Because regular physics students are studying work and energy right now, i was helping him out by teaching what i learned in ap physics. That is, as i said, draw freebody diagram.

Physics Journal #7

This weekend we went to Hawaiian Bryans and played pool. There were many things i could relate to physics in pool. As a matter of fact, i became better at pool (i think) because of physics. Because we learned that the direction of the target ball after the collision is proportional to the direction of the line that connects centers of cueball's and the target ball's masses, i was able to put in more balls than before because i had better idea of where the ball will go. However, due to friction, spin of the ball, and other extraneous factors, the ball didnt go the way i expected to go all the time. Also, the cue ball didnt always go perpendicular to the direction of the target ball went after the collision. that is probably because the mass of the cue ball is a little greater than the mass of the target ball. Another factor that made the error is probably spin. Because we didnt learn spin of the ball yet, we cant really analyze how that could affect the direction of the ball.
I was also aware of friction force between table and the ball. Without it, the ball would go all over the place without stopping. It would be interesting but it would be stupid to play because you can do nothing other than wait for the balls to go in the pocket.

Physics journal #6

At senior camp, we played this high calibur table game uniquely designed for the 21st century lifestyle. This game is called bulletball, and the objective of the game is to get the ball (or some kind of object) past your opponent by utilizing your forearm and/or hand. We played 6-man bulletball with water bottle that was provided at the camp. As we hit the bottle back and forth the table, i remembered that i could use my physics knowledge to analyze how this works in physics. As we hit the ball, we are using momentum and impulse. Momentum of an object is greater if the mass is greater and since the bottle we used were much greater than a ping pong ball that we normally use, the momentum was much greater. Also, just like the lab we did, as the bottle came to me, i thought to myself, if i hit the bottle to the other side and assume that velocity is positive, then the velocity of the bottle coming near me is negative. Therefore, if i apply a great force in that, i could hit the ball so much faster to my opponent. So i did apply a lot of force so i could hit the bottle with great velocity and get it past my opponents.

Physics Journal #5

This weekend, we had our xc meet at kamehameha school. Because of the rain, the ground was insanely muddy and it made us have hard time running the race. Because of the slipperliness, one of our runner fell down right after the race began. When the officials stopped the race because of an unadvantageous start, my friend and i discussed about how this has something to do with physics. We both agreed that the ground has a low static friction coefficient. Because of that, as the force we put in to kick the ground increases, there's higher chance of our shoes slipping on the ground. We discussed on what the best way to deal with this problem. One of my friend said it would be better to run from heel to toe because there would be more surface for the shoe to grip on the ground. However, i disagreed with that because i thought the longer time we have our foot on the ground would increase the chance of our foot slipping. Therefore, i suggested to run on the toes and kicking the ground more perpendicular to the ground than we usually do because if we kick the ground almost perpendicular to the ground, the friction force would be at its max. However, if you ran from heal to toe, it would be difficult to do that because you must exert a force in a backward direction which would lower the normal force which would lower the friction force, making the shoes slip on the ground.

Physics Journal #4: Work

Work is network times displacement of an object due to the force. this week, we had track workouts for our cross country. I ran 800m interval 8 times, so I ran 6400m (8x800=6400, which is equavalent to running running 4 miles) but my displacement is 0m (because I ran around track which means I ran back to where i started 16 times in total). In physics, our whole workout that we put so much effort on requires no work since the final displacement is 0m. It's a little bit disappointing because it feels like I'm wasting my time doing the same amount of work as not doing anything. Thinking like this made me feel like running on track is a bit retarded because you could just not run still have the same amount of work done from running around track, at least in physics definition. On top of that, it's not really me pushing myself, it's the earth that's pushing me.

AP Physics #3

We learned more about dynamics this week. We learned about friction force and so on. Running sure is full of dynamics because running also involves friction force (kind of obvious but). In order to run, i need friction. Otherwise it will be impossible to go uphill. What enables me to kick off the ground is friction. When I'm running, i never go past my shoes' max friction force. I know this because I never slip when I'm emitting force as i try to run. If my shoes had very little maximum friction force, i would not be able to put that much force to run.
Also, another example would be the tire of a car. While i was in my friend's car, i noticed that the car's tire's maximum friction force is insane. Insane because the car was parked on a steep hill (around 50-65 degrees compared to flat ground). Normally, objects would slide down the hill but since the tire's friction is great, the car stays where it was parked. I forget but i remembered that in the reading it said that the car's tire's friction coeffiecient was around .87 or something like that.

AP Physics journal: Dynamics

Just like what we discussed in lectures, i felt the difference in net force while i was going up and down using the elevator. Though i was too shy to explaining to others why we are feeling the difference in weight in the elevator, i went over the reason why in my head.
another example of physics-related thing i experienced this weekend was, again, during the XC race. Because i kick off the ground while going down the hill (in other words, jumping down the hill), i am in the air for a little while. Because i accelerate down due to gravity, while i was in the air, i felt very light (less weight). This is exactly like that elevator example. Because there is a downward acceleration, while im in the air i feel less weight. However, when i landed, i felt extra weight on me. It is because my downward acceleration suddenly went down to no acceleration (deceleration). So i wondered wouldnt going down the hill be a good workout too? i think so lol

First Physics Journal

Two weeks of physics class had passed and I have managed to survive this course so far. Although I faced many difficulties, I still enjoy learning physics. However, I must say Problem Set #2's last problem was hard...How do you find the range for the shortest range?! Anyways, I'm starting to catch on with this whole equations and all, so hopefully I do good on the next test (none of that stupid mistakes i made in the first one...like thinking that fat line in the middle of the graph was axis lol). I'm guessing that 3D movement is exactly like what we're doing right now except we have three independent equations...or maybe not, who knows lol.

When i was running a xc race on saturday, i was actually calclating the average velocity of the pace i was running in and i tried to find the final velocity and acceleration in order to achieve that increase in velocity. my first mile was 6 min and 26 seconds and the race was 2.6 miles. So in order to run faster than 19 min for 2.6 miles, i had to run 1.6 miles in 12min and 34 seconds. i was actually amazed i was thinking through these kind of things in the race. Unfortunately, i decelerated because i got a side pain right after my first mile so i finished the race poorly.