Reflection

A couple years ago, taking pictures of our reflections in mirrors was one of the funnest things to do. This is my friend and I at karate practice. I never realized that our reflections have something to do with physics. The image is created from light hitting off the mirror and back to my eye. The angle of incidence is equal to the angle of reflection when an object is reflected to form an image of that same object. Although my image looks like it is being created inside of the mirror, it is actually the same distance I am from the mirror, but behind the mirror. Physics always pops out of no where.

Transformers Extra Credit

Waimalu Park, Sear's Distribution Center, H3, Newtown Estates, Times Coffee Shop in Kailua, Entrance to H3

Electromagnets

This spring break, I went on the California College Tour, and we went to Disneyland on one of our free days. When we went to ride the Twilight Zone in California Adventure, I remembered what we learned in class about electromagnets controlling the falling elevator. An electromagnet has the same characteristics of a permanent magnet, except an electromagnet works when electricity is present, instead of all the time. A magnet is attracted to the elevator, and since it is controlled by electricity, it can be turned on and off. This lets the elevator drop at a high speed for one moment and come to a stop at another moment.

Sound

While in my car, I remembered what we had learned in class so far about sound waves. In this video, the song is being played at a lower volume, then I turned the volume higher. Looking at the singer's voices, the two have different frequencies and amplitudes. Jason Mraz has a lower frequency (lower pitched), while Colbie Caillat has a higher frequency (higher pitched). They also sing some parts of the song louder than others, which would make the amplitude of a sound wave bigger. Although the singing changes frequency every time the singer changes notes, the beat of the song remains the same. Therefore, if I were to analyze one of the beats, the frequency would remain the same at any volume, but as I turn the volume higher, the amplitude of the sound wave would increase. Physics is everywhere.

Motor and Electric Meter Extra Credit

Magnets

This is a picture of the side of my refrigerator. My mom put a lot of these heart magnets on it, but I never realized they were related to physics. An object is a magnet when it creates a magnetic field and exerts a magnetic force. A bigger magnetic field creates a stronger magnet. The magnets have a north and south pole on them, and they are attracted to the metal of the refrigerator. They are strongest at their poles, instead of the center.

Circuits

While I hung out with Robbie this weekend, he drove his mom's car. However, he couldn't drive the car at night time because one of the headlights burnt out, so he had to switch cars to drive me home. Anyways, I found this is related to exactly what we are learning about in Physics class. A circuit must be complete in order for things such as light bulbs to function properly. As shown in this picture, the light bulb in the headlight does not work because the filament, that once connected the circuit in one path of traveling electrons, burnt out, so the circuit is no longer complete. Even though the car battery is still working to light the other lights on the car, that one headlight does not work because of the unclosed circuit.

Voltage & Extra Credit

This weekend for the BJ Penn fight, we had a bbq. Everyone brought all different types of foods. Anyway, while I was watching my dad grill all the meat, I noticed he had to just push this small button to fire up the whole grill. This made me wonder how one small button can start up the gas grill. Then, I realized the button was a electronic ignition and that it had a small voltage duracell battery powering the button. We just learned that voltage equals potential energy over charge and that it is a ratio. Since charge is measure in coulombs, there are a lot of electrons involved in lighting a grill. Even though a small dry cell battery was used, it was able to light the grill. I read that a bbq lighter uses something called piezoelectricity to generate a nice spark that lights the grill. Piezos are some kind of crystals. When you apply pressure to them, you get a charge separation within the crystal and a voltage across the crystal that is sometimes extremely high.




For this experiment, I tried it many times. It wouldn't work on myself, my mom, my sister, or Blake, so I finally tried it on one of my dogs, Chloe. With Chloe, I could see how the charge balloon made the water bend a little bit. The bending of the water can't be seen very well in the video, but if you listen, you can hear the difference as I bring the balloon closer and farther to the faucet water. Since the balloon received electrons from Chloe by friction, it changed from being neutral to being negatively charged. Water is made up of polar H2O molecules, so when it came closer to the balloon, the positive charges in the water separated from the negative charges and attracted towards the balloon, causing it to bend towards the balloon. My sister and I are going to try this again with a different type of balloon and hopefully it will be more evident.

Center of Mass/Moment of Inertia

This is a picture of my clothes rack where I hang some of my clothes because my closet is too full. As you can see it it standing perfectly fine, but this was not the case before i re-arranged the clothes I put on it. At first, I put all of my heavy jackets on one side and my light dresses and tops on the other side, and one night the whole rack fell over while I was sleeping. I did not expect this to happen but then realized it was because the center of mass was outside of the support area, which is in the middle of the rack. The mass should have been centered towards the middle of the rack instead of having heavy clothes on one side and lighter clothes on the other. It also could be seen as the heavier side creating a torque, and since there was more moment of inertia on that side (due to its bigger mass), that made it easier to fall over. After whole clothes rack toppled over, I realized I should evenly put my lighter clothes on it.

Torque

This weekend while I was driving, I recalled what we had learned about torque in class and how the steering wheel of a car has torque. Torque is a force that causes or opposes rotation. It causes angular acceleration and makes an object want to change its state of rotation. While turning, there is an axis of rotation and a force being applied by my hand. The radius of the wheel is the lever arm. By using torque, I am able to steer and turn the car in the direction I apply the force in. I never realized that torque is responsible for how I steer while driving. Physics is everywhere!

Impulse

I never stopped to realize that karate has something to do with physics. Every time I throw out a punch, I am exerting an impulse that is equal to the amount of force I put in to the punch multiplied by the amount of time I exert that force for. Impulse is equal to the change in momentum. Punching someone is almost like a sticky collision and momentum is conserved no matter what, so the initial momentum should equal the final momentum. Also with this in mind, almost all of my punches exert the same impulse, but the stronger punches are the ones with more force done in less time, rather than the ones done with less force in more time, so quick jabs are much more effective in sparring. I always knew that fast punches seemed much stronger than the ones I took my time on, but I never knew the reasoning behind this until we recently started learning about momentum and impulse.

Potential and Kinetic Energy

In class, we are learning about potential and kinetic energy. At the top of the slide before I started sliding down, my potential energy in relation to the bottom of the slide is equal to my mass times 9.8g times the height from the top of the slide to the ground. My kinetic engery at this moment is zero because kinetic energy is equal to half of my mass times velocity squared, and I have zero velocity. As I started sliding down the slide, my kinetic energy raised because I was gaining velocity, but my potential energy lowered because the height was lowering. Althought the potential and kinetic energy was changing as I slided down, the total energy (potential + kinetic) remained constant at any point. This explains the conservation of energy. At the bottom of the slide, I came to a stop and my potential and kinetic energy both became zero.

First Quarter Reflection

Physics is a very challenging course. I never expected it to be this difficult. I usually am a person who enjoys math more than memorization. I liked Chemistry last year much more than Biology because it involved more math problems. I thought Physics would be the same, but it makes me think very hard just to solve one problem. All of the different forces and their directions are quite confusing. Although tests and quizzes are difficult, I enjoy the labs in this course. They are very fun. I also enjoy the class environment. I like how it is laid back, and we get the chance to work with everyone. I'm pleased with my performance in this class so far, but I still hope to do much better by studying and practicing more problems. My goal for this course is to be able to do every concept with ease. I'm scared but very excited for what's to come this school year in Physics and expect to have fun, and all of this is shown in the picture above from Halloween a year ago.

Newton's 1st law

In 8th grade, we were taught about Newton's Laws and learned that his first law stated that an object in motion stays in motion and an object at rest stays at rest until a net force acts upon it. I wasn't really sure what this all meant in 8th grade, but learning about his laws more in depth in physics helps me to understand his laws a bit more. According to Newton's 1st Law (law of inertia), every object continues in its state of motion until acted upon by a net force. The object's state of motion is either at rest or at a constant velocity. At this state, the object's net force is zero. While at a sleepover, we piled the drink bottles up on each other, and they were all at rest. Because of Newton's 1st Law, the bottles stayed at this state of motion until a net force (someone's hand) broke this state and pushed the bottles over. This incident happened a while ago and was something we did only for fun because we were bored, but it is interesting to know now that there is physics related to this.

Projectile Motion

While playing tennis, there is actually physics related to the sport. Projectile motion is "the movement determined by an object's initial velocity and the constant acceleration of gravity." This works when there is zero air resistance. When I hit the ball, it starts traveling across the court at a certain velocity until it gradually changes due to gravity. The ball bounces on the ground, and then the other player hits the ball back. The horizontal velocity put on the ball never changes throughout the ball's flight. The time it takes the ball to bounce isn't affected by the amount of horizontal velocity the ball has, it is depended on the initial velocity and gravity put on the ball. This projectile motion may be more obvious when a lob is hit because the force of gravity acting upon the ball's initial velocity can easily be seen. The ball is hit up and falls back down because of its acceleration of -9.8 m/s/s, but the ball never changes its horizontal velocity until it hits the ground because there isn't a force changing it.

Velocity and Acceleration

This past summer I went to Las Vegas with my mom, sister, and Blake. While we were there, I rode the roller coaster at Circus Circus with my sister. This ride showed the physics of velocity and acceleration. Velocity describes the speed and direction of an object, while acceleration is any change in velocity over a period of time. The roller coaster's velocity was zero at the start of the ride. As we started moving up the track, it started to accelerate from rest to a slow speed and then maintained that speed for a constant velocity until we got to the top of the slope. After reaching the top, we accelerated again until we reached the peak velocity and couldn't accelerate anymore. We maintained this velocity throughout the ride until we started to slow down and experienced negative acceleration towards the end. The ride finally came to a stop for zero velocity again. We moved in the forward direction for the entire ride. We ended at the same starting position as the beginning, so there was no displacement during this ride.