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!

Unit 4

Today, we wrapped up unit three and moved on to unit four: 2D kinematics. A "solve for one variable" type of kinematic equation quickly turned into a more complicated multi-step process. This unit made understanding physics much harder.
We learned to set up a 2D kinematics equation with a T graph. (Shown below.) Some of the most important things to remember are to separate x axis things from y axis things (vegas rule) and time is a value of y (aYer).
If I were to dive off a diving board 5 meters above the ground, going forward at 1.5 m/s, how far would I be from the bottom of the diving board to the place I landed?

___x___|___y___
     ?m    d    5m     (height of diving board)
 0 m/s/s  a  -9m/s/s(gravity)
              t
1.5 m/s  v              (given)
1.5 m/s  vo  0 m/s   (given)

Now I have to solve for time using d=1/2at^2+Vot
5=1/2(-9.8)(t^2)+(0)(t)
1.02=t^2
1.01s = t
This means it took 1.01 seconds for me to hit the water.

The next step is to solve for distance of x using d=1/2at^2+Vot
d=1/2(0)(1.01)^2+(1.5)(1.01)
d=(1.5)(1.01)
d= 1.515 m

My horizontal range is 1.515 meters.

Quarter 1

Applying Units 1, 2 & 3:

Unit 1:

I miss those days way back in unit one where we learned about scientific notation. I would give anything, like, let's say, 56 million dollars, or 5.6 x 10^7,  to go back to that section. It also seems like forever since we learned about dimensional analysis. It has been a long seven days of summer school so far... That is:
7 days x 24 hours/1 day x 60 min/1hr x 60 sec/1 min = 604,800 seconds! Wow. These are quantitative observations about the things we learned in class. If I were to make a qualitative comment, I would say that the things we are learning are always easy to understand, but that may not be an accurate statement.
(Source: tumblr.com)

Unit 2:

Speed, a scalar value, is based on total distance traveled, while velocity is based on distance traved and direction traveled in (vectors, displacement). Distance, or total path length, uses the SI accepted value of meters. This can be applied when thinking about swimming.
Swimming is a really boring sport because you don't travel as fast as runners do, even if you work just as hard. Your breathing rate increases at a constant rate with distance (constant velocity). The more minutes you swim, the more breaths per second you have to take. Swimming back and forth in a lane 25 long to practice is frustrating too. You don't end up any farther than where you started, so your displacement is zero. It seems no matter how fast you go and how hard you work, you never really move anywhere except within your lane.

Unit 3:

This picture shows many cars backed up on Manoa Road. They were all stopped at a red light. Once the light turned green, the cars in the front of the line accelerated to start the car moving forward. Once they turned, they slowed to a constant speed. Now when the cars in the back of the line saw the cars in front of them go, they had to accelerate too, but not quite as fast as the cars in the front, otherwise they would hit the car in front of them. Once they reach another red light, they will have to accelerate backward to break and stop the car. If one of the cars fell off a ledge, gravity would take place. At around 9.81 m/s^2, the car would accelerate downward until it reached the ground.

Unit 3

In unit three, we covered a lot of material on acceleration. It was a difficult concept to understand, since it is built upon velocity, time and distance, of which were just taught to us several days ago. It is also hard to read the graphing of yet another idea, acceleration vs time. 

Source: YouTube 

(http://www.youtube.com/watch?v=5C5_dOEyAfk&feature=player_embedded) 

In this video, Commander David Scott tests Galileo's theory that an object's mass does not affect the velocity at which it falls (as long as there is no air resistance). Since he was on the moon, wich is essentially a vacuum, the feather and the hammer fell at the same rate and hit the ground at the same time.

Physics could also be applied to rain. I always thought that the larger the drop -> the heavier the drop -> the faster it falls from the sky. Now I know that using Galileo's theory, the mass of the drop is independent from the velocity it travels at. 

Extra Credit

Extra Credit!
This is my mom reading my blog post on acceleration. She is also following it under "mpb".

Acceleration

Today, we learned the basics of Acceleration. This included many confusing equations, like d=1/2at^2+Vot, V= Vo+at, and V^2=Vo^2+2ad. One that was more easily understandable is acceleration equals the change is velocity over change in time (The final velocity minus the original velocity over the final time minus the original time) .
If I were to apply this equation: Say that a car sped up from 1,000 meters per second (around 37 mph) to 2,000 meters per second in twenty seconds, and it took the car ten seconds to get from zero meters per second to 1,000, I could find the acceleration.
2,000 meters per second minus 1,000 meters per second is 1,000
Twenty seconds minus ten seconds is ten seconds
1,000 meters per second divided by ten seconds equals 100 meters/seconds^2
100 meters/seconds^2 is the acceleration :)

Unit 2: Continued

Today we learned more about unit 2, the study of kinematics. This class mostly focused on the graphing of position vs time data and velocity vs time data.
We did an activity with a motion detector that sent out clicks that would bounce off a wood block we were holding and send it back to the machine. It sent out constant signals, so when we graphed our data, it created a pretty accurate line. Using the motion detector, we had to try to re-create a path that was drawn for us on our graph. A motion detector like this one can be used on both a velocity vs time graph, and a position vs time graph.
Dolphins, like the ones in my video (took in Osaka, Japan) have built in motion detectors! They make sounds that bounce off their targets to find objects and food. It's also helpful for their sight, since they can't really see well in murky water. It's called echolocation.

Unit 2

In this unit, we focused on Kinematics. We learned all about velocity, average speed, distance, slope, vectors, acceleration, speed, magnitude, more graphing, instantaneous vs average, and more units.

This picture shows a car traveling in one direction at a relatively fast speed. Opposite the car is another car traveling in the opposite direction, also moving at a fast pace. If I were to graph this, it would look something like this:

The point of intersection would be at the moment I took this picture.  (Sorry, backwards) The slope of this graph (distance vs time) is velocity (d/t=v). Velocity is meters per second in this case. I drew the both slopes steep to show that both cars were moving fast. Since both of these cars are ending up in different places, they not only have distance traveled, but displacement too. Distance is defined as total path length, while displacement is the distance between where you started, and where you ended up. If you start and end in the same place, your displacement is zero.

Unit 1

In Unit one, we covered accuracy, precision, the metric system, graphing, scientific notation, dimensional analysis, qualitative and quantitative observations, and pendulums, periods, and made various lab hypotheses. I chose to write about the pendulum lab because I liked that section the most.

In this experiment, we tested the effect of string length, angle of drop, and mass of object on the length of 5 periods. I hypothesized that all of these factors would cause the period length to increase.

However, our experiment data shows that mass of the object on the end of the pendulum and the angle of drop has no effect on the length of the period, although string length and angle of drop both increase period size.

The person on the swing is like a pendulum. It does not matter how heavy the person is on the swing; the period length will stay the same if the angle and length of chain holding the swing up remains constant.

If people were swinging on two different swing sets of different heights, then the person on the higher swingset would have a longer period.

http://www.photogalaxy.com/photo/fotogrllt/2/

Letter & Picture of Introduction

Hi I'm Jess. I love to travel, especially outside the country, and I love taking pictures of everything. Attached is a sample of my work (which represents me?). I guess if I were to pick a favorite subject at school, it would be photography. But if I had to pick a favorite core class, it would be science. Or maybe English. I don't mind writing, both stories and papers, but I also really like science, although mostly biology and chemistry. I just finished a year in geometry, and next year I'll be in Alg2/Trig. I don't know what I hope to get out of this class because I'm pretty sure it revolves around math... & I'm really bad at math. I hope to get a good grade.