Sunday, January 10, 2010

Newton's Second Law


Newton's Second Law has been the toughest for me to understand out of the three laws. Newton’s Second Law helps us understand moving bodies by linking the cause and the effect (or force and acceleration) in a definite way. In the definition of Newton's Second Law it states that acceleration of an object is proportional to the net force and inversely proportional to the mass of an object. I found that very confusing until I learned the equations a=ΣF/m and ΣF=ma. These equations are the key to understand Newton's Second Law.  The equations and FBDs helped me solve problems that involved gravity, tension and applied force. After mastering the equations I came to understand how things are inversely proportional to each other.  For me though it was not just knowing when which equation or knowing what forces to use, but understanding why I would use each force/equation in a problem. This I think helped me get a better understanding of the second law. I may understand Newton's Second Law now, but I did have trouble mastering it. I have found a number of things difficult about the second law. One thing that I found hard was the direction the object was moving. If an object is moving upward the tension force (the force is usually tension) comes first in the equation. But when the object is moving downward the gravitational force comes first. In the beginning I did not understand this; I thought one force comes first no matter what. But after I came to understand that the direction the object is going affects the order the forces in the equation this problem was fixed. Another thing I had a bit of trouble with was inclined plans, I again had to refresh myself on SOH CAH TOA, but after that angles and inclined plans were a breeze. Just because I have survived this class for 1/2 a year does not mean I go without mistakes, my problem solving skills are stronger but not bullet proof (yet). I again have to remind myself to SLOW down. I have tendencies to rush through the problems as fast as I can. But I have gotten much better at slowing down reading the problem, thinking what I know, and using that information to solve. FBD's have been another small problem for me, in some problems I neglected to draw one. Since making many errors I have learned to make and FBD for every problem, even if not required to help. The making of an FBD helps show me how to set up my equation the right way. 

5 comments:

  1. There is a great amount of detail, which is very well expressed. You have a couple of misspelled words and some gramatical errors. I reccomend copying and pasteing this on to Microsoft Word so you can see what should be fixed, but other than that, a great, well written reflection. ^^

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  2. Great posting! As Daniel said you put a lot of detail in your analysis and did a fabulous job in reflecting about this unit!

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  3. Thanks so much Daniel for your help, especially for the spell check!

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  4. I like what you have so far. The only thing I would suggest is some type of visual to go along with some of the things that your are explain. Maybe a simple picture next to the part with tension and gravity.

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  5. This is also long winded and could be trimmed down as well as the sum of the forces is not accurately summed up by mass*acceleration. That is a special case. The most accurate equation is actually change in momentum over change it time. If you haven't gotten there yet its okay, just understand EF=ma is not completely accurate. and on solving problems keep the good work up with the FBDs and immediately in the start of each problem write down the appropriate equations.

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