Reflection on Physics - the end

What is physics?

Physics is science dealing with energy and motion that relates to real life examples and occurrences. Physics is everywhere in our world, from the sky to the ground, and how to get there in between. Physics is the explanation for nature, and how our universe works.

What did you learn from this class?

From this class, I gained so much knowledge. As there were times when I wanted to break my pencil in half and run around the quad, there were equally, if not more moments where I was laughing nonstop. This class was so compressed, I was worried that I would get behind and perform poorly. However, with help from my friends, I got help when I needed it. Mr. Blake would always patiently listen to my questions, and help me figure out what I didn't understand. Unfathomable concepts became basics to my physics brain. Before the course, I didn't expect anything close to the summer I've had.

What did you like about the class?
I absolutely loved how each concept was relative to something in our daily lives. Doing our homework was pretty easy, because we could identify the concepts from class. Mr. Blake gave us such clear examples and made sure we understood each idea before we left for home.

What could be modified to improve on the class?
I think some labs could've been modified or replaced by a lab more related to the unit idea.

Commentary/Feedback?
I had a lot of fun and learned so much, thank you Mr. Blake!!

not as it appears - unit 10

Refraction is the changing of wave speeds due to changes in mediums. Today, we did many demos and worksheet problems to learn how these certain refractions look in real life. The index of refraction is represented with the letter n. n = c/v, which is the speed of light in a vacuum (3 x 10 ^8 m/s), divided by the speed of light in the medium. Some indexes of refractions we learned, are air (1), water (1.33), glass (1.5) and diamonds (2.42). If we put this in the c/v = n equation, you can get each speed of light in the medium.
Refraction is dependent on the medium, where if there is change in 2 media, bending will occur. Snell's law is an equation that can be applied to refraction. With this equation, we can find the angle or the index of refraction. The critical angle happens when there is change in media. All critical angles are relative to the normal.

when will my reflection show? - unit 10

Today, we did a lot about mirrors, colors, shadows and reflection. There are two types of reflections: specular and diffuse. A specular reflection is a smooth surface relative to its' wavelength. A diffuse reflection is a bumpy surface relative to its' wavelength. Most objects are diffuse, and because of it's not smooth surface, it allows us to see the image. As I said in the last blog post, a mirror is opaque, and gives off a specular reflection of light. In this picture, I can see my full body in the mirror, because the mirror is greater then half the length of my body. My feet to my head reflect in the mirror, which reflects back to my eye, which is how I see my whole body. If I were skipping towards myself in the mirror at 3 m/s, the image of me in the mirror and my real body would approach each other at 6 m/s. Because I am using a flat mirror, there is no center of curvature so light isn't conveyed. Because the light isn't conveyed, I can see my reflection very clearly and well.

what you see - unit 10

Today we learned that when you are looking at an object, you aren't actually seeing the object. Instead, light is reflected off of the object, which is what you see. Electromagnetic waves (EM), or electromagnetic radiation, is radiation consisting of self-sustaining oscillating electric and magnetic fields at 90˚ angles facing each other and at the direction of the motion of the em wave is transmitted through a medium such as air or water. It does not require a supporting medium and travels through empty space at the speed of light.

We also learned that objects are either transparent or opaque. If they are transparent, the em frequency is allowed to go through it. If opaque, the em frequency is NOT allowed to go through. The little trinket I bought in china town many years ago on a field trip, is an example of a transparent object. I know that it is transparent because light can go through it, and I can see from one side to another if I look through the glass. Some objects that are not transparent, are mirrors, books, carpet etc.

unit 9

 

Continuing with the topic of waves, today we learned about sound waves. A few key ideas we learned, were that object want to vibrate, and that noise is a sound that is incoherent. Also, sounds need a medium to travel through.
Using a tuning fork, we did multiple labs showing us how sound travels. The average human can hear about 20 Hz - 20,000 Hz. Animals who can hear higher frequencies are called ultrasonic, whereas the opposite, hearing lower frequencies are called infrasonic. 

In this picture that was taken 5-6 years ago, I am with the cutest water mammal, the dolphin! Out of curiosity, I looked up the range of frequencies they can hear. I found that it was a much bigger range (to no surprise), 250 - 150,000 Hz!

Using the beautiful creature, I created a sample problem that shows how to find the frequency, given the speed and wavelength.
If a wave has a wavelength of 2.17 meters and the speed of sound in water is 923,580 m/s, what is the frequency a dolphin hears in this water?

V= ƒλ
92,580 m/s = f (2.17m)
f = 42,664 Hz, 42.7 kHz

Motion of the Ocean - Unit 9

Today we were introduced to waves and wavelengths. From chemistry, I was somewhat familiar with what waves were, and how they contributed to our world. However, there were a lot more aspects and details that we didn't learn, that make "waves" a topic a little more difficult to understand.

I found that when Mr. Blake talked about the ocean's waves in terms of the physics waves, I understood the whole concept a lot better. Below, I will define words that are affiliated with waves, but in terms of the ocean water.

Frequency: The number of waves it takes per one second.
Hertz: Units of frequency (if 3 small waves came in one second that would be 3 Hz. # of cycles/secs)
Amplitude: The height of a wave measuring from sea level.
Wave speed: How fast the wave comes
Wavelength: How long the wave is.



Interference is when two waves meet in the ocean. There are two types of interference: Constructive and destructive. Constructive is when two waves coming from opposite directions meet and create a very large wave, whereas destructive is when two waves coming from above and below meet, creating a completely flat sea level when the leave.

The girl in the picture below is cruising in the water with her doughnut floaty. If 2 waves pass her in three seconds, the speed of the wave can be measured as followed:

V= ƒλ
V = 3/2 Hz(2.5 m)
V=1.5(2.5)
V= 3.75 m/s

What is it's period, or the time it takes for one complete cycle to occur?
T=1/f
T = 1/1.5
T = 2/3, 0.67 sec

Bottle Rocket analysis - quarter 3

What design features worked?
           The size of the fins and how we wrapped duct tape around them seemed to work fine. A few time the rocket landed on a fin and it came off, because the fins were only attached to the bottle by hot glue, but after we duct taped the glued fins to the bottle the fins never came off. The bottle itself never broke apart. Our first nose cone was very good because of the thick paper we used. However, it got stuck in the tree and we were unable to retreive it. We didn't have any more of that paper so we had to use a thinner construction paper. We wrapped the cone in the duct tape too, but it was still flismy, and crushed easily. The only design that didn't work was the parachute. For some reason, we couldn't get it to come out of the cone. Although we tried folding it and placing it inside the cone various different ways, it was never effective.

Launch condition - amount of H2o PSI?
         When we launched it twice in the morning (8ish), there was no wind. We used a lot of water (about 1 L) and realized that it had too much water and it was weighing it down, which constrained it from reaching a higher height. We then tried a little less water (about 3 party cups full of water) and it worked a lot better. We tried to get as much PSI or pound/square inch as we could. We ended up with about 100 or 120 PSI, the highest PSI we could get.

What this taught you about physics and otherwise.
           I learned that there are always variable you don't know about, or don't realize that exist. It's very hard to manipulate your experiment when you are outside. I also learned that expirements are very hard to reproduce, and very hard to predict the outcome - the outcome is different every time!
           Otherwise, I learned that maybe there is such thing as fate, and whatever that's meant to be will happen! I also realized how frustrating it is when something doesn't go the way you planned it and you know why but can't make it change (like with the parachute). Lastly, NEVER GIVE UP! You never know what might happen!

Our highest time in the air: 9.1 sec. Overall, I am very proud of our rocket. We got the second highest time in the class.

carlos - quarter 3

Today we added gazmos and gidgets to our bottles in attempt to making it soar in the the air for at least five seconds. We were allowed to add a nose cone, parachute and fins. With very few limitations (the liquid has to be water, cone must be attatched to bottle etc.) me and my partner blake designed a bottle rocket.

 

Materials used: 

Two 2 L bottles

Lots of duct tape

String
Hot glue gun
Scissors/exacto knife
Clay

Not identical, similar for the most part though.

Plastic bag
Poster board

To elongate our rocket for stability, we used the middle to end section of one water bottle and sealed it to the bottom of the other bottle. We cut out triangular shapes for our fins following an outline found from the internet. We then taped the fins completely with duct tape, to make the fins more firm. We hot glue gunned the fins to the bottom of our rocket, careful to not melt the plastic of the bottle by filling it with water. Our cone was made out of poster board (paper material but much thicker than construction paper) and we just rolled it up so it looked like a party hat. We put a ball of clay along with a dime and balled up tape in the top of the cone, to add mass. Lastly, the hard part: the parachute. Although we tried to follow instructions found online on how to make a parachute, we ended up folding the plastic bag in half, and cutting out a half moon that was hand drawn. It seemed a little small, but we decided on testing it out first. We put eight or so pieces of tape going around the plastic bag, and then hole punched that section so we could string the parachute to the cone. We added tape so the string wouldn't rip through the plastic bag and would be more durable. We did the same thing with the tape and hole punching on the cone. The strings from the parachute and were taped down to the bottle.

When we tested our rocket out, we were dumbfounded that it stayed in the air for so long (about 8 seconds but we didn't time it.) And this was without our parachute deploying. We are very content with our product, but we still have some work to do :(

We named our baby rocket Carlos in case you were wondering!

weeerk - unit 8

Until now, we have been learning about work, or any change in energy. Today we learned about power, and how that is the result of work divided by time. The units are joules/sec, also known as a watt. During our laboratory, we learned that objects that are more massive take more power to move. This is because the rate at which work is being done is greater than the rate of an object that is less massive. The difference between work and power, is that work is the amount of energy an object uses, and power is the rate of the energy being used.

The cost of electricity is about 20c/ Kwh, the following equation is the cost of one light bulb left on for ten hours straight.

0.21 Kw * 10 hrs * 0.20 c/Kw hr = $0.42

potentiality - Unit 8

To blow off steam from a tough day of physics, I went to go work out at my gym after school. During my speed bag lesson, I noticed that there was a pendulum right before my eyes! The speed bag located on a hook (to allow the bag go back and forth) was actually a pendulum! This unit was about work and to understand it, a pendulum was used to show how work is neither created nor destroyed. Where the pendulum lays when no one has touched it, is the equilibrium point. We can call this 0m, and nowhere on the pendulum no matter how it is pushed can go past the equilibrium point. When the weight of the pendulum is brought up above the ground at a certain point and released, the weight should go back and forth and never go higher than the dropping point. When the weight of the pendulum is suspended in the air, it has potential energy, because there is distance for the force of the ball to come down. Because it isn't at its equilibrium point, it has more than 0 potential energy. When the weight is released, the potential energy decreases as the kinetic energy increases (an inverse relationship). When the pendulum is swinging back and force, the equilibrium point is when it'd be going the fastest because there is no force working against it/for it. If you had the same situation (suspending a pendulum above the ground) but pushed the weight of the pendulum forward, no longer will it return to the same spot. It will go back and forth faster, and end up higher than the dropping point. In this video of me speed bag boxing, I am putting energy into the pendulum to make it go back and forth. Because I hit it with a great amount of energy (and the weight is very light) the bag goes back and forth quickly, and hits either side of the top of the pendulum.

the smell of success should NOT be the smell of eggs! - Unit 7

For this project, I was assigned to my partner Nalei. When we came up with an egg catcher, we agreed that in order for there to be less force on the egg (so it won't break), we had to somehow increase the contact time, and decrease the the impulse.

What we did: We used a plastic container and cushioned the bottom and sides with shredded newspaper. There are about ten sheets of newspaper on the bottom of the container, so there is something between the hard plastic and the shredded newspaper. Towards the middle of the container, there is a cup of cotton balls surrounding the egg. The egg is wrapped in one sheet of newspaper, and is sitting on the cotton balls. On top of the wrapped eggs, there are more cotton balls and newspaper.

What we used:
1 plastic container 23 cm in height, 13 cm in width, 17 cm in length.
20-30 cotton balls
15 sheets of newspaper

Why we did: The four inches of newspaper were supposed to cushion the eggs landing, and create a separation between the egg and the plastic. The cotton was supposed to increase the contact time, as well as create more of a cushion. Wrapping the egg in newspaper was supposed to protect the egg more.
...success?

No, I failed. A lot of the mass came from the lid of the plastic container, which we weren't expecting to land on the bottom. The lid split open, and the egg couldn't handle all of the force.

delta P - Unit 7

In this unit, we learned about momentum. In order to find momentum, you must know the mass and velocity. To find the change in momentum, you will have to know the average force and change in time. To be put simply, momentum is just inertia in motion. When we look at momentum between two objects, some things never change. If the two colliding objects have different masses, they will still have the same force of impact, the impulses would be the same, the changes in momentum would be the same (same thing as impulse, changes in momentum and impulse are two interchangeable words), however, the speeds of the two objects will be different (because mass is inversely related to velocity).

Here is a sample problem: A 50kg man is running with a velocity of 10m/s north onto a 1000 kg car. When the man is in the car, the velocity is 15 m/s north. What was the velocity of the car after the man jumped on it?

Equation: MboyiVboyi + McariVcari = (Mboy + Mcar) Vf

50kg(10m/s) + 1000kg(15m/s) = (50kg+1000kg) Vf

500 + 15000 = 1050Vf

15500 = 1050vf

Vf = 14.76 m/s

all work, no play - Unit 7

After our long three day weekend, we got right back into physics by learning the kinematics of collisions. In this picture that mysteriously looks very similar to the one Mr. Blake took, our class is having a water balloon contest. This is to prove that objects have a limit to how much force they can stand. Like someone falling off of a 20 story building, "It's not the fall that kills them, it's the landing surface." What this quote is saying, is that when you are falling, your body increases velocity and the final force you land with is so great that your body can't handle it; therefore you die. Well in this fun activity we did at the end of class, we had to catch the water balloon in such a way that would cushion the water balloon so it wouldn't burst. We learned that if we increase the time where the balloon was caught, the less force would impact the egg. In the equation: delta P/change in time = avg. force, we see that force and time are inversely related, indicating that the more time it takes to catch, the less force will be exerted on that object.

I learned many concepts in this class that I wouldn't have learned in any other class. Most of everything I learned is on other blog posts.
Physics is enjoyable for me because I am finally learning the "behind the scenes" of what's going on when objects are in motion. Many questions I had about why something happens have been answered by taking this class. For example, I always wondered why a ball would still bounce up and down in your hand when you were in a car. Why wouldn't it go flying straight through the back window? I am glad I took this class over the summer. I am also really glad I have friends who I can enjoy this difficult class with. I can rely on them for help, and they make it fun. Four to six hours everyday seem like nothing!
In physics, the concepts were really hard for me to understand the first time around. Since this class is so compressed, we had to learn everything really quickly. The ideas and concepts kept getting harder and harder. This is an ongoing challenge for me, but I've fixed the problem by asking Mr. Blake and Colin for help, asking my wunnerful table mates and going to extra help after school. Because I don't understand everything as well, I need to spend more time on homework.

may the forces be with you, balanced - Unit 6

These are pictures of me dog sledding a couple spring breaks back in Whistler. It was super duper fun, so if you are in Whistler or anywhere where you can dog sled, I highly recommend it. The dogs are super cute too!

Let's look at the forces on the sled. Because it is on the ground, there is a normal force exerting upwards. They also have weight, which is pulling them to the ground so they don't fly away. Even though these two forces exist, they cancel each other out, so one force isn't acting more than the other one, leaving it balanced. Because the dogs are pulling on the sled, there is tension pulling the sled forward and tension pulling the dogs back. The last force that exists is friction. Friction is what makes the dog sled slow down and come to a stop. Although you cannot see in this picture, the dogs are not keeping a constant velocity, as they constantly accelerate the further they go. This means that tension and friction are unbalanced, because there is more tension making the sled accelerate.

when push comes to shove - Unit 6

Now that I understand forces with two objects a little more, I am aware that I made the learning process a little more difficult than what it is, and in reality, it is much more simple. The trick is knowing if the objects are in constant velocity or in constant acceleration. By knowing which it is, you can determine which object is exerting a greater force. If the velocity is constant, you know that the blocks are exerting an equal force. This is because the force from the push for the 45 kg ball becomes the normal force for the 10 kg ball, making them have the same force. Although the push isn't directly going to the smaller ball, because the big ball has that force and it is touching the smaller ball a normal force going left is created for the smaller ball. Friction on the smaller ball and friction + normal force on the bigger ball pull back on the balls, preventing it from accelerating, which is why it has a constant velocity. Although the balls are going to the left, they have a constant velocity and have equal forces on them. If I were to draw a force diagram for each of the balls during the motion it would look like this:

This is a picture of me holding a balloon blowing away (this was the only picture I could find that had tension! Because balloons are filled with helium, it is very light, lighter than air, which is why it wants to float up. I tried challenging myself, and hopefully it's correct!) We know that there is tension going in the downward direction because the object is floating upward and it is attached to the string underneath it. Since air is heavier than the helium in the balloon, there is very little weight. The tension is what balances the weight so the object stays idle. Because the object is hanging by a string and not sitting on a surface (unlike the other picture), there is no normal. Lastly, there is another force, wind that is making the balloon blow in a certain direction. If I am correct, the diagram should look like this:

ukerub technique - Unit 5

In class today, we went into depth about Newtons three laws of motion, free body diagrams, and vectors. My last blog post talks a lot about the definitions, but for this post i want to see how they apply to daily life. In class, Mr. Blake mentioned how when a car veers to the left, the people in the car actually lean to the right. This was something I had always learned about, and just now I realized that it's physics baby! This is my explanation of what goes on in the car when this "jello" game happens. Let's say when in the car, it is going a constant velocity, so therefore it isn't accelerating. However, when you turn your car to the left, you are accelerating because you are changing the direction (assuming that you are not changing the velocity when you turn, even though you should decelerate for safe driving). Because of Newtons first law of motion, we know that an object in motion will stay in motion unless acted upon by an outside, unbalanced force. So when driving in a car, your butt and feet move the same way the car moves because it is connected to the car, but your head and most of your body isn't, so inertia makes your body want to still move forward, when the car is moving left. Thus, you move in the opposite direction you are going to continue going where you were going before the car changed directions.

standard physics - Unit 5

Newtons three laws of physics:

I. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. 

II. The relationship between an object's mass m, its acceleration a, and the applied forceF is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector.  

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

The first of Newtons laws rooted from Galileo's concept of inertia. This law is stating that an object in motion will continue to move, unless something (a force) is preventing it from doing so. 

     For example, if I were to push a binder across the table, technically it would keep moving if friction didn't exist. Or it could slide off the table and hit the ground where it would stay because of gravity. If it weren't for this law, you could never move an object without losing it forever. 

Basically, the second of Newtons laws is telling us that the acceleration of an object depends on the net force acting on the object and its mass. As the force (like friction or gravity) increases, the acceleration increases; as the mass of an object increases, the acceleration of an object decreases. 

    For example, if an object has a net force of 20N, and a mass of 4 kg, it's acceleration is 5 m/s^2.

Lastly, Newton's third law indicates that in every interaction between two objects, there is a pair of forces acting upon it. The sizes of the forces for each are equal and the direction of the forces are opposite. All you need to remember for this law is that forces always come in pairs and there is an equal and opposite action-reaction. 

     For example, think of a magnet. On a magnet, there is a positive force on one side, and a negative force on the other, meaning that the direction of the forces are opposite. We know that the two forces are equal because if there is nothing magnetic on a table, you can have the magnet facing up or down (positive or negative). If the forces weren't equal, one side would always be facing up. 

 This is the extent of my knowledge, hope it makes sense!

sensei's last words - Unit 4

 Projectile motion gets even more complicated than the vegas rule, and 2 dimensional analysis when angles are added to the word problem. But not to worry, if you know your trigonometry than it's quite easy to understand.

Here is a problem I made up, that involves angles in projectile motion:
   
          If a girl jumps off a rock ledge 5 meters high into a pool with a velocity of 2m/sec at an angle of 5˚, what is the initial horizontal and vertical velocity, how long is the girl in the air, and how far horizontally will the girl land in the pool?

First you have to do the following trigonometry to get the initial horizontal and vertical velocity.








Once you know the horizontal velocity, you can plug that in the XY table as the initial and final velocity on the x-axis. The vertical velocity can be plugged in as the initial velocity on the y axis. Next, we have to remember our rules from yesterday, and find the time in the aYer. That can be done with the "DAT" equation: Dy(m)=1/2 ay (m/s^2) t^2 (s) + Voy (m/s) t (s)
or
5m=1/2(-9.8m/s^2)t^2(s) + 0.17 (m/s) t
5=-4.9t^2+0.17t
4.9t^2-0.17t+5=0
(do quadratic formula)
t=1.03

Once you know the time, find the distance of the x-axis using the DAT equation again.

D=1/2(0)1.03^2+1.99(1.03)
D=2.58
She went 2.58 meters horizontally into the pool.

Summary statement, a girl jumps off a rock ledge 5 meters high into a pool with a velocity of 2m/sec at an angle of 5˚, what is the initial horizontal velocity of 1.99 m/s and an initial vertical velocity of 0.17m/s. The girl was in the air 1.03 seconds, and jumped a horizontal distance of  2.58 meters.

that's why i can flip a quarter in the car without it hitting my face! - Unit4

Projectile motion took me such a long to understand, so here's my post for as far as i know!
To prove my understanding of projectile motion, i created my own word problem:

An airplane flying 1000 m/s dropped a parachuter and he reached his landing spot at sea level, 600 meters from where the plane was. How high up was the plane?


Answer, 17.64 meters above the ground.

How to solve this answer: First you have to write down the givens in a format showing the x and y axis. You must remember to follow the "vegas rule" (whatever happens on the x or y axis stays on the x or y axis respectively...). You should have a table of givens that look like this:


X-axis table explanation: the initial and final velocity is the same because the plane is not accelerating.  The plane isn't accelerating because, because it's velocity isn't changing.

Y-axis table explanation: the original velocity is zero m/s^2 because the parachuter was sitting in the plane, he wasn't moving and therefore didn't have any speed before jumping off. Acceleration is -9.8 m/s^2 because the parachuter is being pulled by gravity (-9.8 m/s^2) in a downward motion (according to the positive and negative is in arrow drawing.)

In order to find the height of the plane, we need to find the time it took first. Time is equal n the x-axis and y-axis, because we learned that objects travel at the same speed no matter the direction they are thrown at.

Finally, to solve the equation, use the DAT equation, or d=1/2at^2 + Vot using the givens from the x-axis.
You should get 600m = 1/2 (0m/s^2)t^2s + 1000t

600 = 1000t, t= 0.6
Once you get the time, you can plug it in the DAT equation again, but this time use the givens from the y-axis.
You should get Dm= 1/2 (-9.8m/s^2) 0.6^2s + 0t
 D=1/2(-4.9)(3.6)
D = 17.64 meters. 

This is not a picture of me parasailing. I'm parachuting.

The height of the plane was 17.64 meters when the parachuter jumped off!

Q1 accumulative

We learned a lot in 2 weeks! I never imagined knowing so much physics in such little time.

Unit 1: The first thing we did, was compare mass, angle and length to a pendulum. We did this by doing the "Period of A Pendulum Lab", and discovered that angle and length have a direct relationship, whereas mass and periods have an inverse relationship. All of these reltionships can be drawn out on a d-t graph, which measures distance vs. time. Next we learned the 5 different types of graphs. 1) no relationship [line is horizontal], 2) directly proportionate [linear diagonal starting from origin], 3) inversely proportional [a curved line starting at a relatively high and ending at a relatively low distance], 4) proportional to the square of x [the right half of a U shape] and 5) proportional to the root of x [the top left side an o]. A few more things we learned (and didn't go into great depth on) are scientific notation, the difference between accuracy and precision and dimmensional analysis.

Unit 2: Unit two was all about kinematics and motion maps. Using many key words, we learned how to graph the motion of an object given its' description. Some key words include scalar, vectors, displacement, instantaneous speed, instantaneous velocity, constant velocity, acceleration, avg. speed, avg. velocity, velocity, and position. The most important thing we learned, is probably the 3 graphing rules; The slope of a DT graph equals velocity, the slope of a VT graph is acceleration and the area under the curve of a VT graph is displacement.

Unit 3: Unit three was still about kinematics, but focused on a certain type of it, acceleration. We learned from the acceleration activity lab that the relationship between position and time is position equal time squared. After knowing how to graph a VT and DT graph from the previous unit, we learned how to create an acceleration graph using the VT graph. If the slope of a VT graph is going negative at a constant rate, then there is a negative horizontal line in the AT graph. Same thing for if it is going at a positive constant rate, the slope would be horizontal at a positive velocity. If there is no slope in the VT graph, this means that it is not accelerating, which means there is a horizontal line lying at zero on the AT graph. We also did a couple of labs on free falling objects. When you are throwing an object in the air, it is accelerating downward so the velocity slows down the higher it goes up.  When the object is at the highest point, it is no longer accelerating, so the acceleration is zero. Then it is falling back down at a relatively similar time to when it was thrown up. The object accelerates as it moves closer to the starting position. So when you throw the object and when you catch it is when the velocity is the fastest. Lastly, we learned that earth has a gravitational pull of about 9.8 m/s^2, which is why the object slows down as you throw it up. Because you are throwing it up (away from the ground), gravity wants to pull it back down, so the object is accelerating in the negative direction, slowing it down to a stop.

That's about it, we learned all this in 10 days; it was a whirlwind!!

The earth moves at a constant velocity of 107,300 km/h around the sun. It does not accelerate in the positive or negative direction.

galileo's theory on acceleration - Unit three

Continuing from last unit, we are learning about acceleration. A type of acceleration is gravity, and the acceleration of the earth is about 9.8 m/s^2 (in downward motion.) Galileo Galilei was the scientist who discovered that our earth has a gravitational pull, and that two objects of different mass will fall at the same speed when dropped from the same height.

I proved Galileo's theory by repeating the experiment. I have two orange caps, one significantly bigger than the other. From the same height (1 meter) I dropped both of them and saw that they reach the ground at the same time.  This shows that the acceleration of the two objects are the same.

If I wanted to find what the acceleration was for caps, I would subtract the original velocity from the final velocity and divide it by the change in time.

No need for speed - Unit 3

Today in class we briefly went over acceleration. Acceleration is the change in velocity divided by the change in time.
I uploaded a video of my car going going down Kalanianaole Highway, to show that the car accelerated and decelerated. Although the video isn't real time (it was sped up and slowed down in iMovie), you can see that the car is going downhill in the beginning, and then running on a flat surface afterward. Because the car is going downhill, it accelerates because it gains speed. If the gas pedal was not pressed, the car would have a very high velocity. When the car reached the stop light, it slowly began to lose speed because it no longer had momentum from the big hill. Pressing on the break pedal is also an example of backwards acceleration because the car needs to move in the opposite direction for it to slow down. To keep the car at an average velocity of 35 mi/hour, (from before the hill and past the flat surface) I would have to press on the break going downhill, and then press the gas when I reach the flat to maintain my speed of 35 mi/hour.

extra cred?

i figured a video of my father reading the intro paragraphs for the past two units word for word and sounding ridiculously interested while doing it would earn me serious brownie points.

he's really dorky.

graphs galore! - Unit 3

In unit three, we studied kinematics, which is the study of motion. We mostly looked at graphs in this section, including distance vs. time graphs and velocity vs. time graphs. We found out that just by looking at a graph, one can determine the motion of the object.


I created two example situations of a distance vs. time graph, and graphed it in logger pro to help as a visual aid.
Without reading the two situations, can you determine who traveled more distance? Who had a greater velocity?

Situation A:
A car on the highway moves with constant positive velocity for 4 minutes. Then, it slows down to a lower positive velocity for one minute. It stops for half a minute, and returns to the initial position in 6.5 minutes.

Situation B:
A truck on the highway was 2 kilometers ahead of the car. It moves with constant positive velocity for 3 minutes, before stopping. After 1 minute of standing idle, it starts moving with a constant positive velocity for 6 minutes.

Graph A

Graph B

By manipulating the starting position, velocity, ending point, etc., it changes how a DT graph looks. Because the rate of distance traveled per time changes in both graphs, they do not have a constant velocity.

(The car in graph A traveled farther, but had zero velocity, so the truck in graph B had a greater velocity.)

Playing With Speeds And Motion - Unit 2

In unit 1 we were introduced to derived units and in unit 2 we learned how derived units are used in real world situations. We learned how derived units, which are units based upon a set of units, are used in calculations. Mainly, we dealt with distance (m), time (sec) and average speed/velocity (m/sec). The  equation to calculate the distance, time, or average speed given two of the three variables is as follows:

distance = average speed (time)

We also learned that motion is relative to another object or space. You can not tell if something is "moving" unless you are comparing it to something else. In the video I have below, my friend diving into the pool is moving, relative to the pool's enclosing wall. The water in the pool and ocean are moving relatively fast compared to the stone walls and rocks surrounding it.

Next, we learned about vectors and scalars, which was a rather hard concept to understand. Although the two are similar, they differ by one thing; scalar is a value with magnitude (how much of something you have), where as vector is a value with magnitude AND direction.

Examples:
      Scalar: Brittany ran 1 mile around the track.
      Vector: Brittany ran 1 mile north.

Other key words we learned were position, distance, velocity, and displacement.
Position: where object is located
Distance: total path length
Velocity: how many meters you traveled per second
Displacement: how far from original path

Lastly, we used everything we know about vectors, scalars, displacement, time, average speed, distance, position, and used it to identify motion in a graph. Most of the graphs we went over in class were called DT graphs, or distance vs. time graphs. These graphs showed the velocity of something or the rate of how fast they were going per second.

How does all of this have to do with my video?
Well, in this video, there are three segments of the same clips of a diver, but shown differently. The first segment was sped up, meaning that the diver traveled the same length as the other segments but did it in less time. This increases the average speed, and on a distance vs. time graph, the line would have a positive velocity because the diver is going away from the starting position. The second segment was the opposite of the first, where the diver traveled backwards. If graphed, this segment would have a negative velocity because the diver is going back to the starting point opposed to going towards it. The average speed of the last two segments were the same, so the length of the line in the graph should be the same because the distance traveled per second are equal in both. The third segment is in slow motion, so it has a different velocity from the rest. It took more seconds for the diver to travel the same distance, so the rate or average speed would decrease. The velocity is not the same for all three videos. The displacement of all three videos are the same, because the diver is traveling the same distance, regardless that she is going faster, backwards, or slower.

That was a lot, but hopefully not too confusing. Feedback especially on the last paragraph would be appreciated because it is the section I am unsure of the most!

Is it a bird? A plane? No it's physics! - Unit 1

A qualitative observation of this picture is that the railing is brown, the surface looks smooth, it looks hard like metal, and has many straight edges. Another qualitative observation is that the ocean is blue.

A quantitative observation of this picture, is that there are six big buildings (that are a little hard to see) in this picture. There is also one airplane in the sky, and one crane next to the building.
A qualitative observation of this picture is that the clouds look orange (near sunset) and there is a dark shadow cast on the buildings.

The first picture is a picture of the view I have from my lanai, which can give the reader an idea of how far away the airplane shown in the second picture is from where I took it. The distance from where I took the picture to where the airplane is at this moment is probably about 4 miles away. If I wanted to know roughly how many meters that was I would do the following dimensional analysis:

4 miles X 1.6 kilometers X  1000 meters =  6,400 meters
                     1 mile              1 kilometer

introduction

hiiii :)
I am sixteen years old, and I just got my license last week! I have been putting it to good use :)
I have completed biology and chemistry in the past two years, and will be taking marine biology junior year. Freshman year, I took algebra I and sophmore year I took geometry.

Going into highschool, my father always told me how wonderful it was that Punahou offered so many science courses. At his school, they weren't mandatory so he didn't take as many science classes as I have. But he often tells me how much he regrets not taking basic science classes such as chemistry and physics, so I look forward to learning the concepts he regrets not learning. I believe that knowing basic science helps you understand ideas that might not have to be directly linked to science, which will help me in my adult years. I hope this class will be a fun, easy way of learning all the basic physics concepts.

I chose this photo, a photo of a group of my friends, the "beach kids." It amazes all of us that we can have so many friends and all get along and trust each other. (Because of the mass of all of us, it was nearly impossible to take this picture and even yet, people are missing!). For most events, it is mainly these people that we see, and  the girls are especially tight knit. One would think that 20 sixteen year old girls couldn't get along, (and i'm not saying we do all the time,) but we are always here for each other. Although cheesy, I love these people, and they are my family! What better way of kicking off summer than with a family photo huh?