Reflection~

What is Physics? What did you learn?
It's more like what ISN'T physics...Physics is the study of energy, force, and motion of matter. In my opinion, one of the hardest sciences, because it involves a lot of math. Physics defines the world around us and explains why things move and look the way they do. For example, we know that the sky is blue because of the high frequency particles bouncing around in the atmosphere. When sunsets are very pretty and highly saturated with warm colors, it is because of the mass amount of stuff in the air. We can use physics to explain what seems to be the unexplainable. 
We can also use physics when dealing with simple concepts you get from just living and experiencing life. We all know by this age that things fall due to gravity, and things accelerate when pushed. But by taking this class, we can find the exact numbers that correlate to what we see. I don't think anyone knew any of d=1/2at^2+Vot, V= Vo+at, and V^2=Vo^2+2ad. Now, if we really wanted to, we can predict anything from the distance of a ball rolling off a counter, to dropping an egg three stories and having it NOT break, to keeping a bottle rocket in the air for ten whole seconds! 


What did you think about the class? What could be modified?
It was a lot of fun, but a lot of work in the beginning to get into the fast paced environment. Good thing we had an awesome teacher to help us through the whole six weeks :) I honestly liked this class, despite all the math. I think that our tests could be a little bit shorter.Maybe if we had more quizzes, our test could be shortened.



Commentary & Feedback?
Thanks Mr Blake for an awesome year of physics in just six weeks :) & a thank you to my amazing table group who worked so hard this summer! It's been interesting. We're done guys! We made it through!

Unit 10: Continued - Refraction

Do you see the other little beaker inside this one? No, right? This is because the larger beaker is filled with mineral oil, which has the same index as pyrex glass, which is what these beakers are made out of. There is a smaller beaker that is tucked within the larger beaker. Since they have the same index, the medium they transfer through has about the same speed of light.
What is a refraction? Refraction is the changes in light speed due to the changes in medium. We can calculate this by using the equation n (index of refraction, no units) = c (speed of light) / v (speed of light in the medium). There are many different speeds of light depending on what medium you're dealing with. For example, the n of air is 1. On the other hand, the n of diamonds are 2.42. That's a big difference!
We can also use Snell's law to find out the direction of refracted rays. I don't know how to make thetas and subscript on this website, so I copied this equation from a classmates, but I promise it's in my notes.

Credit: Matt's blog -> http://physics2011summer.blogspot.com/

Unit 10: Continued

Today we learned about the difference between specular an diffuse reflection. Specular reflection is when light is reflected off a smooth surface, such as a mirror. Diffuse reflection is when light is reflected off rough surfaces, such as clothing or paper. The law of reflection states that all angles are relative to the normal.

This picture shows three Mr Blakes! We learned how to make this using two light (slide?) projectors and our new knowledge of the colors of light. In kindergarden, they taught us that the primary colors were red yellow and blue. As you can see, the complimentary colors (colors that are on the opposite ends of the color wheel) of these primary colors are orange, purple, and green. All the colors mixed together makes black.

On the other hand, because of photography, I learned about colors for printing; RGB & CMYK! The primary colors are red, green, and blue (RGB). The rest of the wheel makes the complementary colors, CMYK, or cyan, magenta, yellow, and black. Also, all the colors added together makes white. We had an dye sublimation printer, which uses CMYO to print photographs. O is used in place of K (black). The O is for the overcoat film put on the photograph last that protects it from ultra violet rays and discoloration. Dye sub printers are unique because they skip the liquid phase of the ink when printing (ink goes straight from solid to gas).

Color Models Source: http://en.wikipedia.org/wiki/Primary_color

Going back to the three Mr Blake(s)...he has two shadows correct? Two sources of light, (the green projector and the red projector), so two shadows. One source of light, one shadow. Red and green light, as we now know, makes yellow. This is why the board is yellow. The shadow on the right is red. This is because the red projector is on the right side. His body is blocking the green light coming from the left. Yellow = Red + Green

Yellow - Green = Red

Red shadow. 

The same thing happens on the other side. The green projector is on the left. His body is blocking the red light, so:

Yellow = Red + Green

Yellow - Red = Green

Green shadow. 

Unit 10

We are finally on our last unit! Electromagnetic waves! We leaned new vocabulary too, Transparent and opaque. Electromagnetic waves are transverse and need no medium to transfer through. For example, sunscreen is opaque to UV rays because it blocks them out. UV stands for ultra violet. There are three types of UV rays; UV A UV B & UV C. They are differentiated by their different frequencies. You get sunburn through UV A & B. Thick layers of concrete are opaque to cellphone signal. On the other hand, clear glass is translucent to most light. Opaque means you can't see through it and translucent means you can (mostly).

We also leaned about ROY G BIV. This stands for red, orange, yellow, green, blue, indigo, and violet, (like the rainbow in my picture) from low to high frequency. All the colors combined makes white.

New equations! E=hƒ
E= Energy
h= Plank's constant
ƒ= Frequency
c= Speed of light
c= 3 x 10^8 m/s

Look forward to scientific notation in our song! (:

Extra Credit(:

My mom is reading my blog. Reminiscing...

Unit 9: Continued

Today we covered more about waves and learned about natural frequency. As I mentioned in my last post, sound is a longitudinal wave that needs a medium. We learned today that light travels faster than sound. It takes five seconds for every mile sound needs to travel. A good example of this would be thunder and lightning. The speed of sound can be used in an equation. The velocity of sound is represented by Vs and Tc is the temperature in Celsius. Vs=331m/s+Tc(0.6)
We also leaned about the human hearing range. We can hear from 20KHz, or 20,000Hz, to 20Hz. Anything above 20,000 Hz is considered ultrasonic and anything below 20Hz is considered infrasonic. As we age, our hearing ability decreases. To decrease the possibility of being deaf at an early age, we should avoid listening to music at a loud volume.

Some cool information about thunder & lighting:
"The time between seeing a lightning flash and hearing the thunder it produces is a rough guide to how far away the lightning was. Normally, thunder can be heard up to 10 miles from the lightning that makes it. Lightning heats the air around it to as much as 60,000 degrees, producing sound waves by the quick expansion of the heated air. Since light travels at 186,000 miles per second, you see the lightning the instant it flashes. But sound, including thunder, travels about a mile in five seconds near the ground. If 15 seconds elapse between seeing a lightning bolt and hearing its thunder, the lightning was about three miles away. Lightning closer than about three miles away is a warning to take shelter immediately. Successive lightning strikes are often two to three miles apart. If the first stroke is three miles away, the next one could hit you." 
Source: http://www.usatoday.com/weather/wlight1.htm


A couple vocabulary terms:
Natural frequency is the frequency at which an object wants to vibrate.

Resonance is the overall adding of wave energies.

Photo:
Nikon D3000
f/5.6   ISO 100   20.0 exposure
5/2/11

Unit 9

Today's new unit is about waves. We learned that waves are just a transfer of energy. Waves and vibration can easily be confused. Waves are up and down motion with direction (in class defined as a wiggle in time and space), vibration is just up and down motion. A medium is a substance by which another substance is carried or transferred. Light and sound are good examples of waves. Light comes from the sun and travels at the speed of light. Light is special because it doesn't need a medium to transfer through. Sound, like radio waves, travel through air (the medium) in longitudinal waves.
There are two types of waves we learned about. Transverse waves, in which energy moves perpendicular to wave motion, and longitudinal waves, in which energy moves parallel to wave motion.

A wave length is measured from two corresponding points, like crest to crest and trough to trough. The crest is the top of the lump and the trough is the low scoop in the diagram. Wave lengths can also be represented by the Greek sign lambda. Wave lengths travel the fastest in the most dense medium. An amplitude is measured by the midpoint of the wave to a crest, as shown in diagram.
We also learned yet another new equation:
v = ƒλ 
V = velocity, ƒ = frequency, as measured in hertz, and λ  = wave length, what I just explained. Frequency is defined as the number of oscillations (cycles) per second.
Credit to: http://img.tfd.com/cde/WAVELEN.GIF

My candid shot of Ari & the spring pen lab is a reminder of what we learned today! In this lab, we tried to knock down certain whiteboard pens by only using a very large slinky and our knowledge of waves. I'll give you a hint: we succeeded using constructive and destructive interference!

Bottle Rockets~ Failure

Our Rocket did best on it's first launch. How sad. We spent the entire class trying to build the perfect parachute buy folding and cutting a ton of trash bags. Everything else about our rocket was fine, as Mr Blake said, we just had to figure out how to get the nose cone off so the parachute could deploy.
We built our rocket out of two 2L bottles, filling them up at a constant amount of one L. We marked the fill line and the PSI that seemed to work, 60 PSI. Everything worked as planned, except for one of the fins and one of the tabs for the nose cone. To start off, we tried launching the rocket as is from yesterday. We started out with a slightly higher one than the day before, 6.51 seconds! They fell off after out second launch today because the rocket landed on them. We came back into the classroom to hot glue gun them back on. Yesterday, we made 6.41 seconds! I thought for sure our new design would extend the amount of time by at least a couple seconds! We put mini fins at the top of our rocket to prop up our nose cone so it can fall off. We also chose to use (out of the many parachutes we attempted to build) a small round circular parachute with many strings attached to the rocket for stability. This was a bad idea. The strings kept getting tangled up and our parachute didn't deploy.
Getting our rocket to stay in the air for more then 10 seconds is actually really really REALLY difficult. We had to account for air resistance, but also include fins to stabilize the rocket. Gravity was tricky because our rocket was so heavy, it would hit the ground so hard after accelerating so fast. This was frustrating because we would have to repair our rocket every time after launch. Plus, getting a parachute to launch is basically the hardest thing ever in life. Never. Again.
Final thoughts & other things learned: I will never ever do this again. There is so much work involved and it's pretty difficult to launch a rocket when we didn't really have a lot of time to build and or test it.

Bottle Rockets~

Today, after a taking a challenging test on Energy & Work, we launched bottle rockets! We had to quickly prepare for our launch day tomorrow by gathering materials for our rocket yesterday so we could put it together today. It was suggested that we use two 2L soda bottles and a plastic cone like the ones from PE as a nose cone. It's hard to really decide on something because we aren't given instructions on how to build one. We can use whatever we want, but we have little guidance on what to do. At least looking things up on the internet is allowed, but it's also hard to try and combine advice from many different sites into one project. Our minimum requirement for time in the air is ten whole seconds! That's really hard to do, even with a parachute!

One of the obstacles in our way was getting the nose cone off so that the parachute could deploy. This is difficult because of the air pushing on the cone when is is shooting up in the air, plus the force of gravity pushing it down on the rocket. We made our rocket out of two 2L straight bottles nestled in one another. For the cone, we cut a large circle of very thin cardboard and formed it into a cone shape. For the fins, we cut three 4x12 centimeter triangles and hot glue gunned them to the lower part of our Rocket. We then layered both with duct tape twice for weight, stability, and structural support.

On our first launch, we exceded the minimum required time amount by 1.41 seconds! Our rocket ended up going for 6.41 seconds, an awesome start for our first attempt. We'll see how it goes tomorrow...

Unit 8: Continued

This is my friend Brian, who has just raced up two flights of stairs with my friend Cathryn. She is a really good sprinter...so obviously, she won. Let's find out the amount of work he does and how much power he exerts using what we learned in class today. He weighs around 130 pounds, while she weights about 105. To convert this to kilograms we divide it by 2.2 kg. Gravity is about 10 meters per second, so we can now find the force by using the equation F=ma.
130 lbs x 1 kg/2.2 lb = 59.09 kg ---> 59.09 kg(10m/s) = 590.9 N
105 lbs x 1 kg/2.2 lb = 47.73 kg ---> 47.73 kg(10m/s) = 477.3 N
They both ran the same amount of distance (two flights of stairs, about 10 meters?), but who did the most work? Who exerted the most power? We can solve for this using these equations:
work (joules) = force • distance
power (watts) = work/time
Cat beat Brian up the stairs, so we know she took less time than him to travel the same distance. She took about seven seconds, while he took around fifteen (Brian is lazy).
Brian's
     Work: 590.9 N • 10m = 5909 J
     Power: 5909 J / 15 s = 393.93 watts

Cat's
     Work: 477.3 N • 10m = 4773 J
     Power: 4773 J / 7 s = 681.86 watts
So what can we conclude? Even if Cat beat Brian up the stairs, Brian still worked more than she did! Why? Because work is any change in energy, while power is the rate at which work is done. This is why Cat exerted more power than Brian.

Unit 8

We started our unit on work and energy! We learned a lot today, mostly centering around the new basic equations and laws on this topic. Work, in a physics sense is any change in energy. You can calculate work by multiplying force and distance. Energy, according to the law of conservation of energy, cannot be created or destroyed, it can only change forms. This means that the sum of the energy in must equal the sum of energy out, for this law to work.
We also talked about two different types of energy, potential (gravitational) energy, and kinetic energy. Potential energy, or PEg is equal to change in energy equals weight, which as we learned earlier is force multiplied by distance, which is like weight (mg) multiplied by distance (height, or h). This energy is shown when dropping or picking up an object from the ground, or from wherever you want to pick to be it's equilibrium point (like desk, chair, floor, etc). In this picture, one of our group members is about to step on a pogo stick. If you picked him up off the ground, you are adding potential energy because he can fall (due to gravity). If you drop him, you are decreasing his potential energy because he falls because of gravity. Kinetic energy, or "KE" is equal to half mass multiplied by velocity squared. Kinetic energy is the energy of motion. If an object is moving, it has kinetic energy. If our group member started running down the hallway, he would have kinetic energy.

In this picture, one of our group members is about to step on a pogo stick.

Egg Drop

Today we did an egg lab! We had to create a safe capsule for a raw egg we are dropping off a three story building (Pauahi). There were various types of capsules; everything from cardboard boxes filled with towels to straws and sponges, to bread.  Our egg did not break! This is because we planned out a capsule that would increase our impact time. Everything we around the egg was used for this purpose.

We bought a round loaf of bread as the center. I thought this would be a good idea, since bread has a soft center with holes for air cushion, and a hard crust to protect it when it hit the ground. We then cut a small hole in the center, and placed the egg in a small Ziplock and then put the Ziplock bag in the hole. We then put the piece of bread we cut off from the hole on top, and taped it over the hole. We then put the bread in a larger Ziplock bag, and stuffed paper towels around it to further increase impact time. We sealed off the bag with as much air inside as possible, to do the same thing. Then we taped a jacket around it to soften the landing.

Unit 7: Continued

Today, we continued learning about Momentum. We saw real life applications of what we were learning throughout the day by visiting a car crash scene (elastic and inelastic collisions), catching water balloons in towels (P=mv), and doing yet another air track lab, which showed us more about momentum and inelastic collisions.

Inelastic collisions happen when two objects colliding stick together on impact. An example of this could be the Air track lab, where we stuck a piece of clay onto one of the carts and pushed a cart into the cart with clay, causing a collision and a resulting two cart object.

Elastic collisions happen when two objects colliding bounce off one another, like a golf ball and a tennis ball. Like the demonstration in class with the rubber ball and the golf ball, when you drop a golf ball on a tennis ball, they change velocities depending on their mass. Since the golf ball is smaller, the velocity from the tennis ball will transfer to the gold ball.

Our lab(?) with water balloons showed us more about longer time of impact, along with the car crash scene. On one hand, throwing a water balloon up and catching it with a soft surface like a towel extends the time of impact with spreads out the force of the water balloon. This makes it easier not to break versus having the balloon hit the concrete. Speaking of, when a car hits a concrete wall, it will crush, like we saw today. Because the concrete/rock wall is hard, there is nothing to cushion the fall to spread out the force. If the car ran into a super huge stack of towels, it wouldn't have been as damaged because there is a longer impact time.

Unit 7

We started off into semester two by learning about momentum. Momentum is defined as inertia in motion. It is calculated by multiplying mass and velocity. Momentum is always conserved, which is a tricky thing to understand. Even if your masses are completely different, like a tennis ball colliding with a windshield on a car, the momentum of both things are the same. The starting and ending velocities will be drastically different, but the momentum that they are going at has to equal out.
Momentum in equals momentum out. So say the tennis ball is B and the windshield (+car) is P.
MbVbo + MpVpo = MbVb + MpVp

We also learned about impulse. Impulse is the average force upon the object multiplied by the time the force is acting on the object. Impulse is also change in momentum of the object. By applying what we just learned about momentum, we can see that:
impact = mass(velocity) - mass(velocity original)
impact = force(change in time)
impact = change in momentum
force = change in momentum/change in time

Through another air track lab, we found out that velocities change when objects collide. This time, our variables were mass and velocity. We used a constant mass of 200 grams to find the changes in velocity when cats collide, and used cart weights of 200 grams and 400 grams to find out more about the relationship between mass and velocity.
It turns out, velocity and mass are indirectly proportional, while impulse and momentum are directly proportional.

Semester 1

It has been a long three weeks struggling through semester one. Fortunately, we're half way done with summer school now! We went through so many topics so quickly! We coved Kinematics, Acceleration, Projectile Motion, Forces in Equilibrium, Unbalanced Forces, and a couple other small topics. I learned all about distance vs time graphs, velocity, the relationship between acceleration, mass, and net force, I learned how to calculate the distance and time of a projectile projected at an angle... I learned a lot of other things; the list could go on and on. More importantly, I learned not to procrastinate, and to ask for help when needed because our teacher is really smart and friendly. 

There are many MANY challenges with this class for me. We are covering a LOT of material everyday, at a kind of fast pace. It's alright I guess, because Mr Blake explains it well. It's hard not to zone out after a while though, because it's just a really long class everyday... It's also difficult to get tested on material a day after we learned it... 


I enjoyed getting to know our class better through the first day of getting to know you activities. I like how our blogposts are set up because they can show us our other classmates work that can help us understand what we're doing. I like the labs we do! They really help in visualizing the concepts we learn in class. 


Through it all, I honestly like this class.

Unit 6: Continued

Today, we expanded more on unit 6. We used an air track in our lab today to help us understand more about the relationship between mass and acceleration. The effect of a pulley is shown in this lab. Pulleys change the direction of a force. We used one on a frictionless surface so we could see the effect of acceleration onto a pulley. By changing the weights of the track weight and the end weight, we were able to graph the differences in acceleration. We noticed that acceleration is inversely proportional to mass, because as mass increases, acceleration decreases. This makes sense because it takes more force to push an object with more mass than an object with less mass. We also learned that acceleration is proportional to force. The more force (in the forward direction) you put on something, the faster it goes.

Unit 6

Today we learned about forces with two objects when they aren't in a state of equilibrium. This could be shown using two objects, like a large heavy bottle and a smaller can. If I push the bottle that is touching the can, the friction from the table will push back on the bottle and can. The bottle pushes me because I am pushing it (forces are equal and opposite because of Newtons third law).

The bottle and can would not have moved and remained at constant velocity (0) had I not pushed the bottle. The can pushes back and the bottle pushes the can. I am the unbalanced force that unbalances the equilibrium, because of Newtons second law.

Unit 5: Continued

In a Merry Go Round, the ride rotates slowly at a constant velocity. The ride cannot accelerate because of inertia & newton's first law of motion. If the small children on the ride are traveling at the same speed as the ride while on it, and then the ride suddenly stops, the children would want to keep moving due to the fact that an object in motion will tend to stay in motion. Especially since there is no seatbelt, there is nothing to protect the kids from flying out of the ride when it stops. Which is why the ride goes so slowly.

Newton's Laws of Motion made much more sense today, after being explained. His first law states that an object in motion will tend to stay in motion, and an object at rest will tend to stay at rest, unless acted upon by an outside, unbalanced force. This is shown through my friend, who is sitting on the floor. Nothing is pushing him or trying to change his velocity, so there he sits. He is in a balanced state because he does not accelerate. His normal force is pushing up, while his mass is pushing down.

Newton's second law states that and object with a large mass will accelerate slower than one with a lighter mass. Acceleration of an object is directly proportional to its force. The faster the acceleration, the stronger the force. For example, if two cars come across a yellow light (same distance apart), and one car is going 25 mph and the other is going 50 mph, the one going faster is going to have to put more force on their break to slow down than the one that is going slower.

Newton's third law is the action reaction law. For every action, there is an equal and oposite reaction. This is shown here with two of my friends. They are playing that game where you're trying to get the other person to fall over by pushing them with your hands. You have to stay in the same place, and you can only push your hands against theirs to make them fall over. Josh has an advantage because he's taller and heavier, so Nina really can't win. But, if they were pushing on each other equally, their positive and negative foce would cancel out, causing them both to go nowhere.

If they were just standing next to each other and I were to try to knock them over one at a time, guess who would be easier? Nina, of course, because she has a smaller mass and would require less force to try and push her out of her state of rest. (Things that are at rest tend to stay at rest unless acted upon by an outside unbalanced force). So while I run up towards her and try and push her, she of course gets knocked down. She gets up and hits me because she doesn't know why I just ran into her. While she is hitting me, I am also hitting her back with the same force. However, because she is a bit smaller than me, she feels the impact more than I do.

Unit 5

June 2010: Shinkansen in Osaka, Japan


Newtons three laws of motion explain the motion of something because something else moves it. These are just my interpretations of these laws; they probably aren't correct.

1. Every body remains in a state of constant velocity unless acted upon by an external unbalanced force.

Everything is always at a constant velocity, unless some force interferes.

As an example, this could mean that inside a car, you are moving at the same velocity as the car until the car breaks, then you get thrown forward (inertia?) because your velocity changes due to the cars change in velocity.

We did an experiment in seventh grade where we put a penny inside a balloon and shook it in a circle motion, and then stopped moving. If we did it fast enough, the penny would keep moving in a circular motion on the sides of the balloon.

2: A body of mass subject to a net force undergoes an acceleration that has the same direction as the force and a magnitude that is directly proportional to the force and inversely proportional to the mass, i.e., F = ma.

When something is pushed forward and accelerates, the mass is indirectly proportional to the force and proportional to the acceleration.

This one is really confusing and I don't really understand. So if a train is pushed forward from rest, the heavier it is, the less force it will take to keep it accelerating?

3: The mutual forces of action and reaction between two bodies are equal, and opposite (whenever a body exerts a force on a second body, the second body exerts a force on the first body. They are equal in magnitude and opposite in direction.

For every action, there is an equal and opposite reaction.

If I am facing my friend, and try to push her backward, and she is trying to push me forward, and we don't move, then our forces are equal. If I succeed in pushing her over, then my force was stronger.

Unit 4: Continued

(Source: Flickr: http://farm4.static.flickr.com/3180/3087734516_dcec92a486.jpg)

To add to the complexity of 2D kinematics, they decided to teach us trigonometry. We learned SOHCAHTOA in geometry last year, but it was refreshing to review it again. SOH stands for sine = opposite over hypotenuse, while CAH stands for cosine = adjacent over hypotenuse, and TOA stands for tangent = opposite over adjacent.

We use when solving for sides of a right triangle using given angle and side measures. The diagonal on the graph that you are using serves as the hypotenuse of the triangle that you will draw. You need to find the horizontal and vertical velocities in order to find the amount of time the projectile was in the air and the horizontal rage that the object flew.

Let's say that someone got a paintball gun and is practicing using it. They shoot a paintball with a velocity of 35 m/s at an angle of 50 degrees. To calculate the initial horizontal velocity, use SOH. (Look at picture for a visual aid)

To calculate the horizontal velocity, take the sine of 40 (opposite) and multiply it by 35 (the hypotenuse) to get 22.49 m/s for horizonal velocity.

If you wanted to find out how long the paintball was in the air, you would have to set up a T table. Use your given data and that data that you solved for into the graph. Be careful not to use 35 m/s (the diagonal velocity) as one of your velocities in the table.

Use the equation V=Vo + at to get your time value. Plug in data. (see picture)

Now, use your time value to see how far your paintball went!