Unit 3 blog reflection

Unit 3 was covered mostly by Newton's 3rd Law of Motion. Newton's third law of motion states that, "for every action there is an equal but opposite reaction." In the beginning of this lesson, we start to understand the concept of forces and interactions. We grasp a concept of forces such as pushing or pulling, but realize that no force or interaction occurs alone. Every force is part of an interaction between one thing and another. For example when a boxer uses his force to punch a large punching bag, the first force on the bag is from the boxer's fist, which causes the bag to dent. However, the punching bag also applies a force back on the boxer's fist. If the boxer was to punch a lighter tissue that was in midair, then the tissue could only exert how much force was exerted on it. This is why an interaction requires a pair of forces action on two separate objects.


After understanding this concept, we then moved to learn about Newton's Third Law of Motion and how it cooperated with action and reaction pairs. Newton's Third Law is summarized by stating, "whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first." But how do we grasp this concept using demonstrations. For example, when you walk, you interact with the floor. You push against the floor and the floor pushes against you. These pairs of forces are the same. So when stating "YOU PUSH on FLOOR" (This being the action) "FLOOR PUSHES on YOU" (This being the reaction) Next, this concept goes further in depth, which helps you understand how actions and reactions work when two object differentiate in mass. The book states, "As strange as it may seem, a falling object pulls upward on Earth  with as much force as Earth pulls downward on the object. The resulting acceleration of the falling object is evident, while the upward accelration of the Earth is too small to detect." When am apple is falling out of a tree the apple is pulling the Earth upward as much as the Earth is pulling the apple downward. Therefore "EARTH PUSHES APPLE DOWN" = "APPLE PUSHES EARTH UP." And to an extent we learn about how force is related to mass and acceleration proportionately with the demonstration of a cannon and a cannonball. When using the formula (F/m) = a, we know that if you have a smaller force then you are going to have a greater acceleration, and if you have a smaller acceleration you are going to have a greater force. We see this when demonstration a cannon firing. The force exerted against the recoiling cannon is just as great as the force that drives the cannonball inside the barrel. During the class we also played a game of tug of war that helped us understand the concept of forces applied. The guys competed against the girls in the game of tug of war, with one exception the guys were wearing socks on the hardwood floor. Anyways, the girls one because they were able to put more force on the ground which allowed them to pull harder.



As we moved into chapter 6, we started to learn alot about momentum. Momentum is simply inertia in motion. Or can also be defined as Momentum = (Mass x Velocity) We learned that a moving object can have a large momentum if either its mass or velocity are large or if both its mass and its velocity are large. One example we used in class was comparing a truck and a small car and seeing how their mass and speed compared to their momentum proportionately. Next, we learned about momentum. We learned that if the momentum of an object changes. then either the mass or the velocity or both changes. This is shown by the quantity force times time interval, or, Impulse = Ft. The greater the impulse exerted on something, the  greater will be the change in momentum. So therefor, Impulse = change in momentum. One example that really helped me grasp this concept was the example that showed that if a boxer "rolled with the punches then the impulse would be less."  This was shown as (little F)(BIG t)= (Big F)(little t) This is where the force over a greater time period would be less as opposed to the force being greater over a shorter time period. Then, we moved into the concept of objects bouncing. We learned that when an object hits something it has an initial impact and if it is not absorbed, has another impact that makes the object bounce off. This creates two forces on the object if the force is not absorbed. The demonstration where Mrs. Lawrence was in the rolling chair and threw and caught a heavy object and she continued to move backwards really helped me understand this more in depth. The final thing we looked at in this unit was the conservation of momentum.
From Newton's second law, we learned that to accelerate an object, a net force must be applied to it. This was generally the same in this chapter except written and explained differently. If we wished to change the momentum we would have to change the impulse. The demonstration the Mrs. Lawrence used where two cue balls were hit together and one stopped and the other kept moving helped me understand in real life terms of how momentum is transferred.


In conclusion, the things that really helped me be more of an in depth learned learner as opposed to more of a surface learner was trying harder on all my assignments. Throughout this unit I believe I only had a few missing homework assignments. I believe I completed most of my work on time and paid more attention to what I was working on. This has helped me grasp new concepts of physics and make me want to learn more. What also helped was the demonstrations Mrs. Lawrence did in class. Sometimes I believe that it is hard to have a grasp on concepts that are read out of a book. It is easier for me learn this way if they are demonstrated with real life problems. My goal for the next unit, and next semester is to try and keep up with this habit that I have developed over this unit and try to understand physics more in depth.