Monday, December 9, 2013

Unit 3 Blog Reflection

      The first thing we learned about this unit was Newton's 3rd Law, which states, Every action has an equal and opposite reaction. This was the starting base of our unit, in which we could refer back to in later works. Shortly after learning this, we learned about action/reaction pairs. An example of an action/reaction pair would be; Hand pushes apple downwards/Apple pushes hand upwards. When doing an action/reaction pair, all you need to do is switch the subject and the direction. One common mistake is that; Earth pushes apple down/apple pulls earth up is not an action/reaction pair because they would both have to be "pull" instead of "push" and then "pull."
      The next thing we learned about was the horse and buggy/tug of war problems. This was a challenge to me at first, but I feel slightly more comfortable now. The question of how does the buggy actually move was presented to us, and we were initially confused. We found out through drawings and explanations that the buggy moves because the horse pushes on the ground with more force than the buggy does. However, the forces are equal, because of Newton's 3rd Law. I will put the diagram/drawing of the horse and buggy problem here for reference. We also did a fun and helpful demonstration where we played tug of war, guys vs. girls, but all of the guys had socks on and the girls had shoes on. We tried our hardest to pull harder and win, but Newton's 3rd Law proved true once again. We ended up sliding past the line because the girls were able to apply more force to the ground.
       The next topic we learned about was forces in perpendicular directions and vectors. I found this to be a fun section and thought it was relatively easy. Vectors are basically the same thing as forces in perpendicular directions, in which one force could be going up and the other to the right. When drawing vectors, the first thing you do is draw lines equal and opposite to the two original lines, so that it forms some form of a parallelogram. Next, you draw a line from one corner to the other, and that is the actual direction the object will go. If solving mathematically, one can use the formula a^2+b^2=c^2.
      Gravity and Tides followed vectors, and the main formula we learned was the universal gravitational force equation, which is F=G(m1m2/d^2). When solving an equation using this equation, it could seem really hard, but as long as you separate the numbers it is not that hard. The main formula for tides was F=1/d^2. The reason tides work the way they do is because the distance from one side of the earth to the moon is smaller, and since we know force is inversely proportional to distance, then that side will have a greater force acting upon it, while the opposite side has a greater distance, resulting in a smaller force. So the reason for tides is the difference in force by the opposite sides of the earth.
      The relationship between momentum and impulse topic had many equations to go along with it. The equation for momentum is P=mv, where P is momentum. The ∆P=Pfinal-Pinitial, and the ∆P is the same regardless if you stop quickly/slowly. Impulse is J, and the equation is J=Forcex∆t, so J=∆P. The big question we asked in this section was, why do airbags keep us safe? The answer is that the airbag increases the time of impulse, therefore the force on you is less, and leading to less injury. Big force=small time/small force=big time.
      In the conservation of momentum, the forces are equal and opposite from Newton's 3rd Law. Conserved momentum means not changed, and there are 5 different equations to remember for this. They will be written out in a picture next to this.
      I found it difficult remembering all of the different equations for each section. I overcame these problems by reviewing the videos, my notes, and my quizzes from earlier. I feel as if I tried pretty hard this unit, however I wish that some of my quiz grades were better. Whether it was not studying enough or stupid mistakes, I will always try to do better on future quizzes. I will do this by studying more and checking over my work.
     I made many connections to real life situations throughout this unit. Momentum and impulse were relevant in the egg toss, and as well as skateboarding and throwing a football.