Week 25 Reflection

This week in physics we continued to review the three different modes of energy: gravitational, kinetic, and elastic, along with friction in different situations. We went over the assessment from the Friday before as a class, which happened to be extremely helpful for me. It was reassuring to know that I was on the right track, but I still needed some adjustments for the reassessment this Thursday (today). Overall, I feel pretty comfortable with the different energies and using the equations to help solve missing variables.

On the first assessment I competed the types of energies correctly in my LOL diagram, but messed up the system by putting both the spring and cart. I found this a little confusing because in the practices from the previous week we put the cart and spring as the system, but it was different on the assessment. In addition, for my pie chart diagrams I forgot to take friction into account and I needed to add su (surroundings) to one of the charts. I also got force and energy confused, which messed up my results for the graph, but I now understand the mistake and the difference between the two. After going over it as a class question by question, I feel like I was prepared for the reassessment today and I felt pretty confident while taking it. I feel that I know the concepts much more thoroughly now.

In addition to reviewing energy, we also began exploring work and power this week. We came to a conclusion that work is a transfer of energy over a distance in the direction of the force. For example, picking up a chair and putting it over your head is work. However, setting it back down on the ground is not work because the chair is not moving in the same direction as the upward force of your hands. The force has to stay connected to the object as well, so that it is the force doing the action, not the object's inertia. Throwing a ball is not work once it is in motion because it's continuing due to its inertia.

We also worked a little bit with power, a rate of energy transfer. Power equals the work divided by the time for the work to be completed. Power is measured in horsepower or watts, but we are going to use watts for class. To calculate someone's power, you have to find their gravitational energy and divide by the amount of time it took them to complete the action. This concept is still a but hazy for me, but we will be working with it more after break.

Happy Spring Break! :)

Week 24 Reflection

To tell you the truth, it's some what hard for me to talk about the cardboard boat regatta because I was so disappointed with mine in the pool. It was literally a 'shipwreck' in the pool after I worked so hard on its creation. The main cause with most of the boats was not having the correct amount of water displaced in order to float. This resulted in the boats sinking. In my boat's case, I don't feel the force of two people in the boat was distributed equally throughout the boat. Our boat was floating, but it was extremely tippy and it ended up flipping is out of the boat shortly after beginning to row. I feel that is the boat covered more surface area and was both longer and wider, it would have resolved this issue.

Despite my disappointing experience, team physics displayed some really awesome boats that did extremely well in the pool. The boats that did well displaced the equal amount of water as the force of the two rowers inside. Then, if the water and the boat exert the same amount of force, then the boat floats. It acts just like a force pair. In addition, knowing that the lowest center of gravity is the most stable, a boat captain could figure out how to position the rowers (on their knees, sitting down, ect.).

Like I said, I'm super bummed about my boat because I worked so hard on it and spent so much time hoping to ensure success in the water. Both Jenna and I got in the boat completely fine and our boat was floating as it carried us. The major issue was that it wasn't stable and flipped after we began rowing. The boat really needed to be wider to help steady it and help prevent any tipping. The boat was lined with two pieces of cardboard on the bottom and had cardboard tubing to add extra strength. Unfortunately, the flipping killed our chances, which is disappointing because I don't feel that the boat is a clear reflection of my knowledge of physics.

Although I wasn't able to row that much, from observing the other groups I found that it was most efficient to have one rower on each side to keep the boat straight. However, the rowing of each side needs to be equal in force to keep the boat traveling forward in a straight path. The time to have unequal forces on each side was when the rowers were turning the boat at the end of the pool. Depending upon the direction, one person had to row harder than the other.

Despite being disappointed, it was an awesome and exciting experience and I can't wait to watch again next year :)

Week 23 Reflection

This week in physics we focused more on energy, its path, and how it can affect velocity. We began the week talking about the three modes of energy storage: elasticity (Eel), motion (Ek), and gravitational field (Eg). We learned that elasticity is the ability for an object to return to its original state and the elastic limit is the maximum amount of elastic energy that can be stored in and object and still allow the object to return to normal. We focused most of our time on the spring analogy. When the apron was at rest, it contained no energy. However, when the spring was stretched by two people, the kinetic energy of the movement of the hands stretching the spring transferred to the spring in the form of elastic energy. The more the spring was stretched, the greater the amount of elastic energy it held.

After learning the three modes of energy storage, we moved on to energy bar graphs (LOL), a graph used to show the transfer of energy in a system before and after a situation. The system is some changed event an the system is the object in question. The first L displays what type of energy (out of the three) the system started out with and what percent of energy was present. The O represents the system in question and the amount of energy either going into it or leaving it. Finally, the last L shows the energy and its amount in the spring after the situation occurred.

Today (Friday) we completed a lab relating the compression distance of the car on a ramp to the car's velocity. The displacement went from one centimeter to five centimeters. It was concluded that if you double the compression distance, the velocity is also doubled. Therefore, it proves that the greater the amount of energy, the greater the velocity.

On a separate note, the cardboard boat regatta is Monday! My group's boat has been completed, but it needs another layer of tape just to better secure it. Wish us luck! :)

Week 22 Reflection

This week in physics was a bit messed up due to the testing, but we started discussing energy and what it is as well as some helpful tips for our boat construction. Today (Friday) we also completed a lab having to do with boats made of foil and the amount of mass they could hold in preparation for our cardboard boats.

On Monday we began discussing energy and different types. We came to the conclusion that energy is transferred to different objects. Kinetic energy, solar energy, and potential energy are different forms of energy, but they all actually has the same energy. For example, a check is in a different form than cash, but they're both money. It works the same way with energy. We also talked about the movement of several objects to display how energy transfers and is present in everyday life. If you kick a whiteboard, the potential energy from your foot turns to kinetic energy, which can turn to frictional energy (heat) as the board moves against the floor. I imagine that we will be talking more about this subject next week and will be expanding more on it.

Today we completed the foil boat challenge and my group's boat held 394.7 grams before sinking in the tub full of water. I learned earlier in the week the volume of the boat needs to be equal to the volume of water you want to displace. A boat floats in water because it displaces the same amount of water underneath it. It's also more likely to float if the boat is bigger because it has a greater surface area to distribute the weight. I am going to take what we learned in class with the equation to figure out the dimensions of our cardboard boat. To do this I will add both the rowers' masses, find out how much water weights that same amount, and play around with the dimensions so the volume equals the amount of gallons displaced. We're starting our boat construction tomorrow, but we need to figure out the specific lengths before we just start building.

Wish us luck!

Week 21 Reflection

This week in physics we truly started and explored our new unit, gravitational force. We began looking at the orbits of the planets, the forces they exert on one another, how distance can affect the force, and hypothetical questions if the orbits were to be altered. This unit is closely related to the centripetal force unit, as the orbits are just like a stopper on the end of the string, and the same rules apply in the solar system.

I learned that the closer the earth is to the sun, the greater the sun's gravitational pull on the earth. And because the earth orbits the sun on an elliptical path, the force acting on the earth changes. So as the earth is farther away from the sun, less gravitational force is pulling it in toward the center of the solar system. This relates to a pair if magnets. The closer the magnets are to each other, the greater the attraction between them, and the farther away, the less pull. In addition, the closer the earth is to the sun, the greater it's velocity. I always thought that we continued at a constant speed as we orbited the sun, but the velocity is actually changing depending on when the earth is in its orbit.

Hypothetical questions regarding the planets and their size/force changes proved to be a difficult topic for me to understand at first, but I now understand it after going over it with the class more. If you were to double the mass of the sun, it would double the sun's gravitational pull. However, if you double the distance between the sun and the earth, the gravitational pull would actually be a fourth of the initial amount. This is because the distance is squares in the equation, but the mass is not. This was confusing in the beginning, but I feel I have a good grasp of the concept now.

Something that really surprised me was that the moon in fact doesn't orbit the earth at all; it only orbits the sun. I couldn't believe I've gone my whole life thinking that the moon orbits both the earth and the sun. It's an illusion that the moon orbits the earth and it is actually a snake-like motion between the moon an the earth. You learn new things everyday :)

I attached the answer key that really helped me prepare for the assessment today!