Constants; V vs. A Lab

I believe that the purpose of this lab was to use what we learned measuring Heart Rates (something that may have seen simple and familiar) and apply it to physics problems. How to analyze graphs, critique them, and how to make them for physics problems are some things that I have definitely gotten better at and/or learned though this lab. This lab also helped me distinguish between the problems I would use for constant velocity (where something is neither speeding up or slowing down but stays with the same speed and direction) and for constant acceleration (where something is either speeding up or slowing down in a constant rate... either constantly going faster or constantly going slower).

In this lab, we saw how a "marble" would react while either having constant velocity or constant acceleration. While using a metronome, we marked the place the marble rolled over at the beat with the metronome. With constant velocity, it showed us that the marble had even spaces in between the marks, where as with constant acceleration, the marks got progressively further apart. This lab is proof that constant velocity neither speeds up or slows down, and constant acceleration only speeds up or slows down at a constant rate and that there is no way for something to have both constant acceleration and constant velocity at the same time.

For constant velocity, one uses equations with "V"s (which stands for velocity) in it, such as v=d/t or variations of the like. With acceleration ("a") one commonly uses equations with "a"s in it, such as d=(1/2)a(t*t). There are many one may use, but in this lab, I found that these two were the most help. 

To support my data, I created a graph of it. This helped me for I then was able to calculate the equation of a line, as well as be able to make predictions with out having to do it myself; it was an amazing time saver. The angle of the line helped me distinguish if the data had constant velocity or if it retained a constant acceleration. 

Velocity Kitten

This video is a, in a sense, non-constant-velocity example. In order to have constant velocity, one much have both a constant speed and a straight direction. In this video, the kitten (as well as the lizards) do not noticeably maintain a constant speed, or direction, meaning not constant velocity. The kitten jumps around, both changing direction and speed, and the lizards seem to walk with a curved/unspecific direction. This video does, however, show acceleration. Acceleration is the change in speed/velocity over a period of time. The kitten will go from standing still, to running around fast, to standing still again. It shows acceleration, though it may not be very constant.

Hovercraft Lab

I was unable to ride the hovercraft, but the students who were able to ride it said that it was strange how well the hovercraft retained the motion of the initial push. If someone was pushed unevenly, the rider would spin until they stopped, or an outside force acted upon them to stop spinning. A hovercraft allows the rider to experience being in a relatively frictionless environment. Unlike a skateboard, or sled, in order to stop, someone had to physically stop the rider, rather than relying on friction to slow the hovercraft down.

When the rider had equilibrium, it basically meant that they were either in a constant state of velocity (not accelerating forwards or backwards), or they were at rest. Inertia was shown though this exercise when it was difficult for the starter or stopper to push the hovercraft. The hovercraft did not want to switch from being at rest to being in motion, and vice versa. When the hovercraft was at equilibrium, it had a net force of 0N, meaning it was neither being pushed or pulled. When the hovercraft was either being stopped or started, it had a net force higher than 0, because it was not at a state of equilibrium.

In this lab, the acceleration seemed to depend on how much the stopper pushed (to accelerate backwards in order to stop) and how much the starter pushed (to accelerate forwards in order to move).

The hovercraft had constant velocity after the starter pushed them. The net force was at 0N, and moving, there for both having equilibrium and constant velocity.

Depending on how much mass the person had, they were either harder or easier to stop. It was shown that the higher the mass of someone, the harder it was for them to start moving, or to stop. Mass is directly related to inertia, meaning the higher mass an object has, the harder it will be to change from being at rest to not, and vice versa.

Inertia Example

According to the glossary in Conceptual Physics eleventh edition by Paul G. Hewitt, inertia is “Sluggishness or apparent resistance of a object to change its state of motion.” This video is an example of inertia in a few different ways. The fist and obvious way is the at rest dishes. They are not in motion to start with, and they stay stagnant throughout this clip. The cloth is pulled out from under them, and they stay still. However, for inertia to be occurring, the subject does not have to be still. The book shelf is another example of inertia, but in this case, it moves. When the boy runs into it, the bookshelf falls to the ground. The boy initiated the movement for the bookshelf when he ran into it. Had there been no floor, the bookshelf would have kept falling due to the force of gravity (it would not miraculously start to go up instead of down unless an outside force affected it), and Newton’s First Law (which essentially is inertia), which states that an object in motion tends to stay in motion unless acted upon by an outside force, and an object at rest tends to stay at rest unless acted upon by an outside force. So, the bookshelf fell down until both the boy’s fallen body and the ground stopped the bookshelf from falling further.

Ready to Grow

This year, I expect to learn the basics of physics. Not only Newton’s Laws, but find out why everyday things happen. Since the topics have been laid out for this class, I have decided to not focus on what I want and do not what to learn, but rather what I am excited about learning. I think that Unit 7, “What Causes Ocean Tides,” sounds fantastic. I have found that most things that relate to the environment or biological beings is far more intriguing than those that are not. Unit 10, having to do with musical notes, and Unit 11, having to do with light, sound amazing, and hopefully we will be able to sample them if we cannot get to them this year.

When I first started this class, I was less than excited, thinking that physics was a boring and confusing subject that was not for me. I have since then changed my attitude and have decided to have a growth mindset about this class. I believe physics is important to learn, because it is around us every day, and while people say the same thing about math and reading, there is actually no way to get away from this aspect that is so prominent but so ignored in our lives. It is also important to learn physics so that one could potentially evade situations wherein one could not shy away from if they had not known how too. And lastly, physics is important for me to learn, for, especially since I was not thrilled to take this course, I believe that it will make me grow in more ways than other classes may have been able to do.

Something I am curious about in physics is how does one make a frictionless environment? I know that hovercrafts are about as frictionless as we can get at this school, but how does one achieve such things. Another question circulating in my head is where in my life is physics, but I don’t know where. Basically, what can I learn that I didn't know I didn't know. And lastly, how can light create so many things? Light is an extremely prominent feature in life as we know it, and I find it interesting that one thing can have such an effect on others.

Goals I have for this course are to try to apply physics at least 3 times a week outside of class and homework, to come to class every day prepared with my book, paper, pencils, and positive attitude, and to complete my homework as often as possible.