The End of Physics

Physics is the science behind everything and anything in motion. Objects, particles, waves, shadows, light, rockets and rainbows. It is the explanation of why things happen.

This was a really fun class. It definitely grew on me. The more we learned the easier it seemed to learn. Its like a language, once you pick it up you can understand it better and better with time. 

I managed to learn a lot in this class considering how short it was. I liked how we just got the basics down, so now i have a basic understanding of what physics is. And i like that everything we learned is applicable to the real world. That factor definitely made me more interested in learning the material. I learned about motion and the forces involved with movement,  acceleration and the role gravity plays, and energy. I learned what work is technically. And lastly, I learned about sound and light waves. Throughout each lesson several questions about day to day life we answered. Simple curiosities such as who made up the order of the rainbow - well that is based on the properties of each light wave. How come when your up to you neck in a pool it looks like you neck is missing? Because of the way light bends in different media. 

I learned a lot of important information that i know i will not be soon forgetting. The best part is that i had a fun time learning everything. We had really fun lab activities, and really cool demonstrations. The work load was manageable so the emphasis of the class was learning and understanding, not just striving for A's.

Unit 10 - Electromagnetic Waves

A flat mirror will reflect a virtual image. That is an image where the light rays do not come together. The distance of the object to the mirror will also equal the distance between the mirror and the image. Basically if you stand in front of a flat mirror you will see yourself as you appear.

If we bend the mirror so that it has convex or concave curvature then images become altered. The object is no longer perpendicular to the mirror and in line with the normal. The normal is always perpendicular to the mirror, but the object is not. Now there is an angle between the object and the normal so that bends the image. This is what makes fun house mirrors so fun and Cloud Gate, this giant bean mirror, so eye catching. We are not used to seeing things warped and stretched like they do in these mirrors. That is the magic of mirrors bending images.

Unit 10

Light waves will potentially go on forever. Unless of course it hits a surface. In that case  it will try to reflect if possible. Specular surfaces are smooth like glass or water. If the surface imperfections are smaller than the wavelength of the incoming light waves the light will reflect nicely. But we do not live in a world with tiny imperfections, so most surfaces are what we like to call diffuse surfaces. These are more rough such as roads or fabric. Light is not as visibly reflected on these surfaces.

My disco ball has a specular surface. Actually each mirror is specular and has its own "normal." A normal is the imaginary line perpendicular to the surface. The angle of reflected light depends on the normal. According to the law of reflection the angle of incidence, or incoming light, equals the angle of reflecting light. A disco ball reflects lights in so many directions because each little mirror making it up is positioned with different "normals." 

Unit 10 - Electromagnetic Waves

Imagine everything you know and recognize as a color actually being several waves reflecting off of a surface and bouncing back to your eye balls for you to perceive. Now that's what color is. When you see red, all the other light waves are being absorbed by the object except for red light. The red light waves reflect and bounce off for you to see. Each color has different wave characteristics such as: wavelength, frequency, and energy. Red has higher energy and wavelength. Since wavelength and frequency are inversely related red has a lower frequency. Violet has high frequency and low wavelength and energy. There is something called an electromagnetic spectrum that displays they colors in order of lowest to highest frequency. When ordered like so, the colors make a rainbow pattern.

Unit 9 - Waves

I learned the physics behind the waves of the ocean. When it comes to water, a longer wavelength has a faster velocity. So those two are directly related. When wavelength directly affects the speed of the wave this is called dispersive waves. Non-Dispersive waves travel at the same speed in the medium regardless of frequency. For example, sound waves are non-dispersive. 

When water is deep the velocity of the wave can be faster, and if the water is shallow, the velocity will be slow. Therefore depth, and the topography of the floor affect waves in so many ways. How they break, where they break, size and speed. For example lets say there is deep water and a wave is moving with great velocity. If all of a sudden the water gets shallow, the base of the wave will slow down but the top part of the wave remains at a high velocity because of inertia. When this happens eventually the base of the wave can't keep up with the top, so the top falls over thus creating a wave.

Unit 9

Today we learned about waves. Waves are all around us, in the ocean, in the football stadium, any sound and light. A wave is a disturbance or oscillation in space and time. Think of it as a wiggle in time and space. There are several properties to a wave, such as frequency. Frequency is the number of cycles that pass in one second. Cycles are measured by wavelength which is between two consecutive identical points of a wave (crest to crest, trough to trough, etc.) We use controlled frequencies to create different waves and make radio possible. Each radio station is represented by a number because that is the frequency of that radio wave. For example 93.9 has 93.9 waves pass in one second. This is frequency 93.9Hz or Hertz, the unit for frequency.

Rocket Launch: Day 2

     We started launching with our old model, small fins and long skinny nose cone with a weight inside. Our launches were averaging three seconds and not doing very well. We made bigger fins and a new nose cone. We made our cone out of sturdier material. Before it was manila folder so we made our new one out of a cereal box. It was wider and shorter. Our launched were improving already but we cut more off of our fins and nose cone to make it smaller. We also cut off the top of our bottle so our parachute could fit into the top of the bottle as well as the nose cone. When it was only being stuffed into the nose cone it was getting packed too tight and wouldn't release. Overall our rocket was doing well even though we didn't get to achieve the ten seconds of flight time. One time the parachute stuck to the tape on the nose cone. One time the string of the parachute got wrapped around a fin so it didn't open up properly. We encountered a new problem with each launch and I think if we had more launch time we could have eventually fixed every problem. The hardest thing was getting the parachute to launch. I think what worked best was having a nose cone on loosely and a piece of the parachute sticking out. Once the rocket started to fall air could fill up this little piece of parachute like a pocket and the rest of it would open up. The hard part was finding a balance. We wanted it to stick out enough to do the job, but if it was too much it would create drag and slow down the initial velocity.
     We were shooting our rocket around 60 psi. That seemed to be when there weren't that many bubbles pumping into our rocket anymore. We filled it up almost half way with water, so just under one liter.
     I learned that the rocket was sensitive to physics, and one adjustment made all the difference. Weight made a big difference when we did not have weight in the tip of our nose cone it didn't work at all. The whole time though we had to consider the risk of weight over design. A more solid nose cone was risky of adding weight. Some risks payed off and some didn't. It really was an experiment. I found that despite the heavier mass, the cardboard nose cone worked impressively better. Since it was stronger it could take the hit better. The force of impact crunched he tip of our nose cone upon landing, but it saved our rocket from being damaged.

Rocket Launch: Day 1

A lot goes into making a rocket. There is the body, the nose cone, the parachute, and the body fins. And they all have to come together. To make it all work out you can use physics to strategically create a rocket. Mass, acceleration, momentum, inertia are just a few things involved. We want our rocket to have a generally lower mass so that it will go higher. The force of gravity will not be as strong against it. We want our rocket to have a sturdy nose cone so that it can help cut through the air. Plus it adds stability and a great place to store and launch the parachute. A possible problem with our rocket, is the fin size. We have small fins and i think they should be bigger. Fins stabilize the rocket and our rocket did skew to the left. We also need to add weight to our nose cone. Right after our rocket reaches its maximum height and falls back toward the earth the weight in the tip of the cone will naturally accelerate toward the ground removing the cap and releasing the parachute. This is why our parachute did not release today.

Unit 8

You always hear the term "watt" used to distinguish which light bulb fits, sort of like battery types, but what does that mean. Well a watt is the power of the bulb. It is the amount of work or energy given in a certain time. So a 50 watt bulb gives off 50 joules of energy per second. We just call joules/second a watt, and that's what a watt is. The higher the watt the more powerful the bulb is.

If you know the watt of your bulb and can estimate how long it is on, you can actually calculate the amount of energy it uses. The power of watts multiplied by the amount of time gives you the amount of energy it uses (w=pt). So if my lamp is on for one week this is what i would do: (50W)(604,800s)= 3.024x10^7 J

Unit 8 Work and Energy

Work is any change in energy. It is determined by force and distance (w=fd) and is measured in Joules. When the water bottle is at rest it's not doing any work. But when I take it off the shelf and put it on the floor it is changing energy, thus doing work. It has potential energy when it is sitting on the shelf and that changes to kinetic energy while I am moving towards the ground. Kinetic energy is the motion of energy. So basically because it is moving it has kinetic energy. When it is sitting on what is considered ground level there is no potential energy, PE=0. The ground level is relative to what the entire picture is, so it can always be changed. If you consider the floor to be ground level then that is the point of equilibrium. But if you consider that this is the third floor and make the bottom floor the point of equilibrium then the floor here has a lot of potential energy The higher an object is the more potential energy there is. So sitting on the shelf has some potential energy but if it were on the roof it would have a lot. 

Unit 7 Egg Drop

We relied on our knowledge of physics to craft a container that would protect our egg from falling ten meters and landing on cement. These are several factors involved: mass, velocity, momentum, dropping distance, falling time and the force of the fall. The goal is to have as small of a force as possible. More force is more damage to the egg. To figure this out we worked backwards, what determines the force? Well force is the change in momentum multiplied by time. To increase the time we wanted something that would cushion and absorb the fall and distribute the force over a longer period of time. The wheel like prism of our structure is made to collapse upon impact and absorb the force so the egg is unharmed. Momentum is a determined by the mass and velocity. Straws have a very low mass. Since they are so light they fall slowly with a low velocity. For all these reasons a straw cage worked well to protect our egg. I am very satisfied with the way our capsule turned out. Maybe something that could be altered is just scaling the size down so its smaller. Then it would have less mass. Although at the same time it would turn out to have less surface area to absorb the fall. So I'm not sure if that would be better or worse or make no difference really.

More of Unit 7

There are two types of collisions: elastic and inelastic. Granted there is an "in between" range of elasticity. Ideally a totally elastic collision would be some sort of uninvented super bouncy ball, or flubber. Basically when two objects collide and bounce off of each other, we can call it an elastic collision. If the two objects become one however, then it is an inelastic collision. This lava lamp, for example, displays both types of collisions. Sometimes the wax blobs will bounce off of each other, this is an elastic collision. Sometimes they combine to form one great big wax blog and this is an inelastic collision. Both of these collisions conserve momentum, the only difference is that kinetic energy is not conserved during inelastic collisions, but we haven't learned about that yet.

Unit 7 Momentum and Impulse

In collisions, momentum is always conserved. So the velocity and mass of the components in a system can vary but the total momentum from before a collision equals the final sum of momentum. How do we know this? Well first off, lets define momentum in terms of physics. Momentum, often represented by the letter p, is mass times velocity (p=mv). We can use this equation to solve for any missing variable. Once the momentum is known, we can apply it to another equation. Average force equals change in momentum divided by change in time. So if my elephant (large mass) and zebra (small mass) run head on into each other at the same speed, we can use the first equation to figure out the momentum of my elephant is greater than the momentum of the zebra. Then I can see which has more force using the second equation. My calculations would show that the force of the elephant  is greater on the zebra than the zebra has on the elephant. All in all, the zebra would get more injured.

Semester Reflection

I learned several equations and how to apply them, but that's all math. I learned that a pulley can change the direction of gravity. I learned what a Newton is. I now can define the difference between velocity and speed. I know the three accelerators of a car- the brake, gas, and steering wheel. I learned that acceleration isn's just speeding up, it also includes slowing down. I learned that every object gets pushed back with as much force as it pushes another object. This is always true, it can never be not true. Thats what physics does, it bends your mind and puts a twist on what you thought you knew. I like the challenge of physics, because it is all applicable to your world. I started having a hard time with forces. That was the hardest part for me so far, but I'm getting the hang of it.