Tuesday, December 7, 2010

The Laws of Motion

       I leaned that there are three main laws of motion, having to do with the forces and motion.
 The first law states that ‘an object at rest tends to stay at rest and an object in motion tends to stay in motion,’ if it is in constant velocity and direction (translational equilibrium) unless acted upon by other unbalanced forces. Or in other words, it helps to predict what is going to happen.  Some other things that a beginning scientist needs to know are units, mass, and weight.  The units are measured in a metric system called a newton (science is always metric). A Newton is the force needed to give one kilogram a one meter to second squared acceleration. Mass is a quantitative measure of inertia, and example is if a one kilo object on earth goes to the moon, where gravity is different, the mass will be the same, it is the weight that is different.
        The third law states that ‘for every action, there is a reaction.’  It is equal forces acting on multiple objects (usually two but sometimes on multiple spots) but opposite in direction. Newton’s second law says that if there is a force that where the net force remains unbalanced, then the object has acceleration.  The acceleration also changes with direction. 
      The second law is about acceleration of an object in the direction of the applied force and explains cause and effect.  For example, if the acceleration is constant, and the sum of the forces remains the same, the mass is a certain amount.  If the mass is doubled, then the acceleration is cut in half because “the acceleration of an object is proportional to the net force and inversely proportional to the mass of the object.”
      What I had found difficult in these studies is finding the equation for calculating the forces from the FBDs. (Especially when on an incline.) 
      My weaknesses are trying to build the equation on some problems (mainly first law (and in that mainly when it is on an incline)) and to figure out what needs to be positive and negative. I think I am trying to rely purely on memorization and fail to get fully the steps to building my own equations. It helped when in the second law we started to put the positive and negative signs.  And I am now able to build the equations without getting mixed up on which to add and which to subtract.


  1. Love the Blog and there is good detail, but you don't have anything about the third law of motion. Also, you should mention pulley problems with the second law.

  2. You have the basics for building a very good posting.
    Your explanations of the laws are incomplete and somehow incorrect. For the first law you say that objects in motion stay in motion, hmmm? is that always the case? what type of motion are we talking about? what if I'm moving in circles?
    The statement of N3L is not just "for every action there is a reaction", this needs to be expanded to be clear. What do you mean by multiple spots? aren't forces always in pairs?
    Be sure to include more detail and applications of N2L such as apparent weight, pulley systems and friction. This is the 'meat' of what we've been doing on the past weeks.
    I look forward to reading your final posting!

  3. Thank you Mrs. Gende and Will for helping me find what I needed to fix in my blog posting. I have elaborated more and hope is explained better.