Unit 1 Reflection

In this unit, I learned about many concepts of physics. 

I learned about Newton's 1st Law, which states that an object in motion tends to stay in motion, while an object at rest will stay at rest, unless acted upon by an outside force. Inertia, or the "laziness" of an object, is the property of an object to follow Newton's 1st Law. The more mass an object has, the more inertia it has.(You can even describe mass as a measure of inertia). Applying the concept of inertia and Newton's Law to everyday life: if a table is set with dishes and such, and the tablecloth is pulled out from underneath the settings, the dishes will remain on the table. This is because both the tablecloth and the place settings are at rest. When you pull the tablecloth, you are exerting force on it which causes it to no longer be at rest. The dishes, however, have not been acted upon by an outside force. Thus, in accordance with Newton's 1st Law, the table settings will remain at rest; the tablecloth is pulled cleanly from the table while the dishes remain in their original spots.

I just mentioned force and how they can change an object's motion. Force, measured in Newtons, is defined as a push or a pull- a pretty broad definition if you ask me. To make things simpler for discussion's sake, we measure the net force of objects. Net Force is the total force acting on an object. 
For example, in the drawing below, a box is being pushed with a force of 50 Newtons. Assuming there are no other forces acting on the box at this moment, the box would have a net force of 50N.

However, in the next image, two opposing forces are pushing on the box. The force from the left is pushing with 100N, while the force from the right is pushing with 50N. As these are opposing forces, you must subtract them to find the net force. 100-50=50, so the net force= 50N.

If these opposing forces were equal to each other, the box would be at equilibrium. Equilibrium occurs anytime the net force adds up to 0 Newtons. It occurs when an object is 1) moving at constant velocity or 2) at rest.

This brings me to the next lesson: velocity. Many people think of velocity as the speed of an object. This is only partially accurate. While "speed" describes how fast an object is moving, "velocity" describes the speed of an object, as well as the direction in which the object is moving. The equation of velocity is: V = d/t (Velocity is equal to distance over time). Velocity is measure in meters per second (m/s) and measures the distance covered in a certain amount of time, as shown by the equation.
If the direction of movement changes, the velocity changes. Thus to be moving at constant velocity, an object must maintain both constant speed and direction. An object is moving at constant velocity when it is at equilibrium (or at rest).

A common mistake is confusing velocity to be the same thing as acceleration. Acceleration describes the rate at which an object is changing speed. Its equation is: A= change in velocity/time interval. Acceleration is measured in meters per seconds squared (m/s^2). For an object to be accelerating, it needs to experience a change in velocity, which can occur one of three ways: 1) changing direction, 2) speeding up, or 3) slowing down. Acceleration can be increasing, decreasing, or constant, depending on the surface upon which the object is moving. If an object has constant acceleration, it cannot simultaneously have constant velocity. An object falling straight down will always have an acceleration of 10 m/s^2, meaning the object increases its speed by 10 m/s per each second.


To calculate how fast an object is moving, you can use the equation: V= at, which shows that velocity is equal to acceleration times time. 

To calculate how far an object has moved, use the equation: d= 1/2at^2, which indicates that the distance an object has traveled is equal to one half of the object's acceleration multiplied by the time it has been moving, squared. Both of these equations describe a relationship between acceleration and velocity, as do the three charts shown below.

The final lesson of the unit was about graphs and applying their equations to physics. The equation of a straight line is y= mx + b. This line, when graphed with time (squared) on the x-axis and distance on the y-axis, can be translated into the equation for distance (d= 1/2at^2). The slope (m) would stand for ½ acceleration, x would correlate with time, and the b is irrelevant from here on out. Using that information, you can visually represent data of an object’s distance traveled by graphing it. Also, you can translate this equation into the “how fast” equation. Since m= ½ a, to find a (in V = at), you would multiply whatever value you’ve found for m by 2. You already would know the value for time, so you could then use the information from the graph to find not only the distance traveled by an object in a specified amount of time, but also how fast the object traveled this distance.

What I found difficult about what I have studied is connecting the topics of acceleration and velocity and then translating this connection into graph-able data. At first I was so determined to understand the difference between acceleration and velocity that I compartmentalized the two concepts in my mind. Really, they cannot be completely separated if you want to fully understand each concept. I overcame this by working out different problems using the equations involving velocity and acceleration and studying over the explanations of each. The light bulb really clicked when I could put into words that “velocity measures the direction and speed of an object and acceleration measures how fast the speed of said object is changing; acceleration is defined as the change in velocity over a given time.” This really makes sense to me, as both concepts involve speed and can be linked in that way. Also, the graphs we worked with this unit were very intimidating to me at first glance. I am not the most computer savvy person and often find myself completely overwhelmed by tasks involving Excel. These graphs, however, made more sense as our class got more comfortable working with them. It helps that I have been working with plotting data on a graph in my math classes for several years now. Going over the correlation between the equations for the graph and the corresponding physics equations clarified the entire process for me; now I understand why I am putting which value on which axis.

I started this unit off very strong, in my opinion. I took detailed notes and gave myself ample time to complete each assignment with full understanding of the material. As my workload increased, this diligence lost some of its initial luster. I continued to work hard though; my homework has consistently been completed on time (save for one instance in which I had only 30 minutes of study hall along with a packed Thursday night schedule), my lab work done with care and elaboration, and blog postings finished promptly and with extensive explanation. Over the course of the year I hope to become more creative in my work and less “cut and dry.” This is definitely an area with room for improvement. My confidence in physics has grown so much already and I enjoy being able to discuss a concept with self-assurance. Not only do I understand the concepts but I am able to apply the concepts to examples we are given in class, etc. When it comes to solving different problems, my skills are varied. I consider writing to be my strongest asset in school. Thus, short answer problems are very easy for me as I find them logical; when I can write out the process it makes more sense. However, the shorter math problems that involve a conceptual formula make sense to me as well and I think I am generally rather good at these. I have a lot of trouble when it comes to “problem solving” questions in which harder math is needed as well as the application of several concepts at once. This is something I need to work on and would like to get better at as these types of questions will show up in my future math and science courses.

My goal for the next unit is to study more frequently by redoing problems I do not understand or have gotten wrong in the past, as well as doing harder level problems of concepts I do understand just to challenge myself and make sure I have taken my knowledge to the next level. I also have a goal to come to conference period at least once a week in the future as a way to make sure I have all my questions answered and every point is clarified. I think these extra steps will boost my grade as well as my confidence in the material.

In the fall, I run cross-country. I love running and spend a lot of my time outside of the season running and learning about the sport. Physics relates to running; I have thought about my acceleration time and time again as I tackle large hills or sprint down the final stretch of track. I enjoy playing soccer just as much, if not more, than I enjoy running. It is not soccer season yet, but 90% of the time soccer is on my mind in one way or another. Going over physics concepts has made me reflect on my game a lot in the past few weeks. For example, the force with which I kick a ball will need to be greater than the force of friction from the field or the air resistance the ball will meet if I were to chip it through the air. Additionally, the velocity with which I kick the ball will influence how far the ball travels and how fast it does so. I cannot wait until soccer season so I can apply these new concepts out on the field. I am also very excited to learn more about the physics involved sports (mostly soccer, but other sports as well, like running, football, and tennis) and why they work the way they do. Who knew athletics and science worked together so well?!

Below is a podcast I made with  group about making graphs and how to use them efficiently. Enjoy!