4.1) The concept of Force

  contact forces -
  field forces -
  
4.2) Newton's First Law
  An object at rest remains at rest, and an object at motion continues in
  motion with a constant velocity (that is, constant speed in a straight line),
  unless it experiences a net external force.       
  
  ΣF = 0
  
  inertia -
  mass -       
 
4.3) Newton's Second Law
  The acceleration of an object is directly proportional to the net force
  acting on it and inversely proportion to its mass.
  
  ΣF = ma
  
  ΣFx = max    ΣFy = may    ΣFz = maz

  Newton - SI unit for force
    1 N = 1 kg . m/s2 

	
  Weight and the Graviational Force
  
  w=mg
  
4.4) Newton's Third Law
 If two objects interact, the force exerted on object 1 by object 2 is equal
 in magnitude but opposite in direction to the force exerted on object 2 by
 object 1
 
 Normal Force - 

 
4.5) Some applications of Newton's laws (talked about in week 1)

  A) Free Body Diagram
  B) The Sum of the Forces is 0
     ΣF = 0

  
4.6) Force of Friction

  coefficient of static friction:  fs ≤ μsn
          
  coefficient of kinetic friction: fk = μkn



Homework 3:
pp. 103 q. 1; pp. 104 q. 1
pp. 106 q. 19; pp. 109 q. 46