Sunday, January 10, 2010

Reflection 2

This is what I learned about Newton's Second Law.  Newton's second law is  Net Force equals mass times acceleration.  In order to use our given information you must analyze the exact meaning of it.  You must know in which direction the object is moving.  Once you now this fact, you decide which forces are helping the object move in that direction and which ones are working against the movement.  All forces moving with the movement are put into the equation as positive, and all the forces acting against the movement are negative.  When you are determining which forces to included you only use the ones that work in the same axis, or along a cord, to find the net force.  In order to help yourself do this, drawing a FBD is useful.  When there are two systems involved your use the sum of the forces to equal Mass(total) times acceleration.  Commonly, in physics problems, there is a Frictional Force that acts in the opposite direction.  The equation to find the MU is Ff=MU* Fn.  In order to find the Fn you use the equation Sum Fy=Fn-Fg equals 0 (if the object is resting on a surface and not falling through the table.)  The unit for MU is Naked!  This is because the units Newton's/Newton's cancels out.  I also learned why air resistance allows for terminal velocity.  When the Frictional air force is equal to the gravitational force, the object can no longer accelerate, causing terminal velocity.  Air resistance is caused by the interaction of a surface and the atmosphere.  The surface area and the speed of the object cause for greater air resistance.

When we first learned about pulleys and tensions I had a hard time understanding how to find the tension in the string.  I finally realized it was as simple as solving for Ft in my sum of forces equation.  As usual, I don't always understand concepts at the first look at a concept.  Frequently I leave the problem aside and then look at it later with a fresh and clean approach. Most of the time this technique works.  

My problem-solving skills have improved since my last reflection.  I think I have put more effort into understanding the material and the homework assignments.  I have made my learning of the material rather than completion a priority.  I think that I have become more systematic with my problem solving than I used to be.  In the past my thoughts and problem solving methods have been very unorthodox, but now I use the same thoughts, but organize them on the page better.  I have become less careless in my work, and I think this has caused me to enjoy math and physics more.

Thank you for your comments!


  1. I really love your resume. But i would suggest that you make clear that it is Net Force that we are talking about. Good work though!

  2. Excellent posting! I second Julius comment about specifying Net force versus just Force.
    Your commitment towards learning versus completion is very profound!

  3. Your posting is really great! Just to improve it...towards the top i think it should be mass TIMES acceleration. I also agree with Mrs. Gende and Julius about the net force. However, overall it is GREAT!

  4. Nice reflections! I like the fact that you are talking about learning. I wish all students had that attitude. Watch out for the idea that friction opposes motion. Sometimes friction creates motion! I think of it as "sliding friction opposes the tendency to slide."