Semester 1 Review

Throughout this first semester (3 weeks) of physics, I have learned a lot. It is amazing how much I know compared to when we first began. I learned about graphing, relationships between time, velocity, distance, and acceleration, and forces. I actually thought it was really interesting how the relationship between the different types of graphs varied, like when each graph was curved, sloped or flat. It introduced me to concepts that really expanded my view on things. I never would have thought some things were possible, but now I understand, like that when something is "decelerating" it is actually accelerating in the other direction. I learned how physics has to do with everything in my everyday life, like how when I punch someone in the face, the person's face is also punching my fist. Force is especially interesting to me. I always kind of look past it. When I push open a door or slide in my socks across the hard wood floor, physics has everything to do with it.

I actually really like physics. I never thought I would and I thought this was going to be a tough summer, but I am pleasantly surprised. it certainly intrigues me, even though I struggle at some points but it is very reassuring when I know that the physics classroom is an understanding environment and I can ask TONS of questions whenever I need help. I like that the fun labs we do, like the slip n slide, the human pendulum, and the rockets. I am a visual learner, so when I see the physics happening right infront of me, it really helps me understand concepts easier.

I had a lot of challenges with unit 6 because there is SO much math. It is still interesting to learn but there is no doubt that I struggle a bit. I think I just need to keep practicing with the word problems, especially the ones where I have to use Fnet = ma and free body diagrams. For some reason, trying to apply that equation is really difficult for me.

Unit 6: Forces That Accelerate

Today we learned a lot more in depth on how to calculate forces using FBD's (free-body-diagrams). It got a lot more complicated when we added pulleys, friction and Fnet. We also learned three rules or steps to follow when dealing with these types of problems:
1. Draw FBD's
2. Find acceleration (a) of the system
3. Choose one mass to find the tension

Here is an example where I use some of these steps to solve the problem:

In this picture, there are two objects, both on either end of a string and in between the objects, is a pulley. A good thing to remember is that a pulley changes the direction of your force, so even though the force of the pulley is going down, it is pulling the blue object to the right. The first step is to draw an FBD of the image, so I have done that in the picture below.

As you can see, I have done an FBD for both objects, each in corresponding colors. The blue object has both the force of gravity and normal force, which balance each other out on the y-axis, but has tension going to the right, which is unbalanced which means that the blue object is accelerating to the right. In this problem, we are not taking into account friction. On the red object, there are unbalanced forces. The tension is less than the force of gravity which means the red object is accelerating downwards. Always remember, if there is no surface, then there is no normal force. Notice how the T's are the same length. That is because the objects are connected by the same string, and therefore the string has the same tension. The next step if to find the acceleration of the system.

In this step we use math (ewww). So far, the only formula we have is Fnet = ma. Luckily, that is the only one we need. Fnet is the difference between all of the forces. After that, it is all math and substitution.

Unit 5: Forces

Today we learned the other two laws of motion. We learned the law of acceleration: the acceleration of an object is directly proportional to the net force of an object, but is inversely proportional to the mass of the object, and the law of action-reaction which is: For every force (action), there is equal and opposite force (reaction). Equal in magnitude, opposite in direction. Basically the first law I stated, the law of acceleration  means that the more mass and object has, the less it accelerates and vice versa. The second of Newton's law I stated, the action-reaction law, pretty much means that there is always an equal amount of force pushing or pulling wither way.

We also learned that a frictional force is a force that impose motion or impending motion. The picture above demonstrates someone about to push the air hockey puck thing (I don't know what to call it). The air hockey puck has a fan underneath so that it is "hovering" above the ground, which decreases friction allowing the air hockey puck to accelerate for a longer distance. The picture below is another example of taking away friction. First, someone tried to go down the dry slip n slide and barely moved, then we added water and it was easier, but when we added soap and water it was very slippery.

We also learned how to draw force diagrams, calculate angled force or tension using the "bureku" technique and trigonometry, and to determine whether forces were balanced or unbalanced. A newton is a unit for weight and is equivalent to Kg x m/s^2 or mass x acceleration of gravity. A good thing to remember is that normals means perpendicular to the surface.

Unit 5: Forces in Equilibrium

This photo relates to unit 5 because today we learned about tension. String forces are tension. Without me holding up the string, the string would fall and the weight on the string gives it tension.

We learned a lot about forces today. A force is a vector quantity that can be defined as a push or a pull. A normal force is a supporting force that is perpendicular to the surface the object is on. Force units are kg x m/s^2. 1kgm/s^2 is equal to one Newton. This leads me to Newtons first law, which is also called the Law of Inertia: Objects in motion will tend to stay in motion, unless acted upon by an outside unbalanced force. Another version of this law is: Objects at rest will stay at rest, unless acted upon by an outside unbalanced force. Inertia is directly proportional to mass, therefore when an object has more mass has a tendency to resist changes in their state of motion.

Unit 4: Projectile Motion (continued)

This photo relates to unit 4 because on Friday we did a lab that required a metal ball to roll down a ramp and land on a specific target. We began the experiment and recorded the metal ball's velocity after the ball hit the flat table. We recorded the velocity twice with devices that were 15 cm apart. After receiving the data in logger pro, we were able to take the difference between all of the velocities and average it out. Luckily, our group got very precise data. Using this information, we predicted where the ball would land after falling from the table by calculating using the kinematic equations. Because of our precise data that we previously measured, our predictions were very accurate because when we finally tested it, the ball landed directly on the 5.

We also did another lab, which involved rockets. In the same way as the first lab, we first tested to see how long the rocket took to land when shot straight using the different caps. Then, using our most precise data, we predicted where the rocket would land using the kinematic equations again, except this time we used a little bit of trigonometry. Unfortunately, we were not as successful in this lab as we were in the first.

Overall, the past two labs allowed us to really work with the equations and predict where things would land mathematically. It was tedious but fun at the same time.

Unit 4: Projectile Motion

This unit we began looking at projectile motion which is combing the vertical and horizontal movement of an object. It is really interesting so far because now I know how it works when I see airplane drop a bomb in a movie. The first thing we learned is that axes are independent (except for time). This rule serves as a basis to many of the concepts we have learned so far in this unit. This rule (aka the Vegas Rule) can better be defined: What happens on the x-axis stays on the x-axis, and what happens on the y-axis stays on the y-axis. We also learned that the velocity for the x-axis is always constant but the the velocity fot the y-axis always changes because of gravity. Like we learned in the last unit, gravity never turns off, so there is always a downward acceleration of 10 m/s^2.

When solving for projectile motion problems, we still use the three kinematic equations, DAT, VAT and VAD except when we collect all of the given information, we have to collect for both the x and the y because projectile motion goes both ways. One rule when solving word problems is to find the time in the ayer. We spelt air like that to remind us that we need to find the time for the y-axis.

The picture above is relevant to Unit 4 because today we did a lab that used this device to shoot out a ball and represent projectile motion. We used the rules we learned today and the three equations to solve accurately and precisely for where the ball would land.

I think this is a fun video to represent projectile motion in a really cool way! (I can't even shoot a basket from two feet away)

Quarter 1 Summary

Unit 1:
We worked a lot with pendulums, mainly to understand the concept making and interpreting graphs, like understand independent and dependent variables. We found the difference between accuracy and precision and covered the standard SI dimensions. We also memorized the different types of graphs, like the linear, square, square root, inverse and no relationship graphs.


Unit 2:
Unit 2 was the start of kinematics, which is the study of motion. The first main rule we learned was that all motion is relative. WE also learned about scalar and vector quantities which are like, distance and displacement. The difference between the two quantities is that scalar is a measurement that has magnitude but vector is a measurement that has magnitude AND direction.

We were then introduced to speed, velocity, distance displacement and acceleration. From this we learned how to interpret motion through words and describe and interpret motion using diagrams and graphs. The first grpah we learned about was the position vs. time graph. The first graphing rule we learned is: the slope of a position vs. time graph is the velocity. Next we covered velocity vs. time graphs. from these graphs we could determine the velocity of an object at any given time. The second and third graphing rule we learned is: the slope of a velocity vs. time graph is acceleration AND the area under the curve of a velocity vs. time graph is the distance traveled. After learning these two graphs and understanding them, we were able to use the data in one graph and translate into another.

Unit 3:
Unit 3 is where we put a lot of this information together. We learned about acceleration vs. time graphs and interchanged them with DT and VT graphs to have three coherent graphs. Now we can take all three types of graphs and interpret all of them. Then, we learned the three main kinematic equations which we call DAT, VAT and VAD. We learned how acceleration can be negative and nothing really decelerates, it just accelerates in the opposite direction.

A song that covers the basics of what we learned so far!

Extra Credit

My mom and I with my physics binder

Unit 3: Continued

We learned more in depth how to analyze various graphs, the relationship between acceleration and gravity, and we reviewed how to use the three equations DAT, VAT and VAD. In this picture we were testing whether which ball would fall first and we found out that they would reach the ground at the same time because they are accelerating at the same place. Even though the balls had different masses and volumes, they still hit the floor at the same time.

We also learned the velocity of an object after you throw it up would be fast, then slow, then it will stop at its peak, then it will come back down slowly, and then speed up again all before you catch it again. If you catch the object at the same place you threw it, then the velocity would be exactly the same except the opposite. On earth, the acceleration is always 9.8 m/s^2 or 10 m/s^2 because that is the pull of gravity.

Unit 3

Starting unit 3, we reviewed a bit about velocity vs. time graphs and then transferred our focus to acceleration. We were first introduced to acceleration when we were taught the second graphing rule "The slope of a velocity vs. time graph is the acceleration". This means acceleration is equal to change in velocity over change in time, which, in units, translates to m/s over s or m/s^2. Acceleration by definition means the change in velocity per unit of time and it is a vector quantity.

This image relates to unit 3 because today we did a lab using skateboards and "danger boards". In the lab we used both boards to roll down a ramp and then we collected the time at different distances. When we graphed the data we found that the boards accelerated as they rolled down the ramp, which created a curved line on our position vs. time graph.

We also learned how acceleration looks on the multiple different graphs. On a position vs. time graph, the line looks curved, on a velocity vs. time graph the line looks like a straight diagonal line, and on an acceleration vs. time graph it looks simply like a horizontal line. Then we learned about the three different equations involving acceleration. They are DAT, VAT, and VAD.

Unit 2: Continued

This picture represents unit 2 because we used this device to better understand position vs. time graphs. This device, called a motion sensor, uses sounds to detect how close or far an object is from the sensor. We used logger pro to translate the data from the device to the computer in graph form at the same time the device was being used. This allowed us to discover the properties of a position vs. time graph. We found that the farther you are from the device, the the higher the graph got, and the closer you are to the device, the shorter the graph got. We found that the slope of a position vs. time graph is the velocity.

We then compared the position vs. time graphs to the velocity vs. time graphs. Velocity vs. time graphs show the velocity of an object at any given time. The slope of a velocity vs. time graph is the acceleration.

Unit 2: Kinematics

In Unit 2, we learned mostly about kinematics. Kinematics is the study of motion. We learned how all motion is relative because technically speaking, the whole earth is constantly moving. This picture relates to the unit because it demonstrates motion. The car on the left is moving relative to the other car. The black car appears to be moving toward the red car, but to the black car, it could seem as though the red car was moving toward the black one. If they are both moving, then it would seem as though the other car were moving twice as fast. We also learned about velocity. Velocity is the distance divided by time or speed with direction. 

Unit 1

This picture really represents Unit 1 because we focused mostly on pendulums. A pendulum is a weight hung from a fixed point so that it can swing freely backward and forward. As you can see in the picture, we tried putting varying sizes of people on the pendulum, which proved that neither mass nor angle of release had any affect on the period because each trial was about 14 seconds long.

From the pendulum lab, we learned how neither mass nor angle of release affected the period of the pendulum, but the length of the pendulum did. The labs also helped us learned a lot about different types of graphs and their relationships as well, especially when we used that information when we graphed our data from the labs. Learning the relations of each graph and how to identify them allowed for us to analyze the lab data more easily. We could then determine the relationship between the mass, angle of release and length of the string and the period.

Introduction

Tennis is my passion. I play tennis almost everyday, especially now that it is summer. Sophomore year, I made the Punahou Varsity Tennis team which is one of my biggest accomplishments. I love playing sports and doing most outdoor activities. I am also a passionate artist. I take many art classes at Punahou  as a possible gateway to a career with creative elements. Looking into the future and college, I am keeping my options open because I have a wide range of interests, including many interests in the Sciences and Social Studies.

So far, in all of the science courses I have taken, I have excelled. I am not always straight A's but most sciences are interesting to me so I always try my best. I did very well in Biology in Freshman year and Chemistry in Sophomore year. I was originally going to Chemistry honors in Sophomore year, but other opinions swayed me and now I regret it.

In Sophomore year I was Algebra 2/Trigonometry and in Junior year I will be taking Pre-Calculus.

I really wanted to take this course to find out whether I like physics because I have thought about careers in engineering and other fields that require physics. Also, the subject has al

ways seemed interesting to me and I am curious. Hopefully after taking this course, I can more easily narrow down my interests.

This picture represents me because this is my artwork. I was inspired to do this piece piece because of the place I live. I love Hawaii a lot it is a big part of my life.