5.1) Work

  The work W done by an agent exerting a constant force is defined as the
  product of the component of the force along the direction of the displacement
  and the magnitude of the displacement.
  
  W ≡ (F cos θ)s
 
  Therefore, if θ = 0;
   
  W = Fs
  
  
5.2) Kinetic Energy and the Work-Kinetic Energy Theorem

  Wnet = Fs = (ma)s     
  
  Wnet = 1/2 mv2 - 1/2 mv02
  
  KE = 1/2 mv2
  
  Wnet = KEf - KEi
  
  
 
5.3) Potential Energy

  W ≡ mgy
  
  where m=mass, g=gravity, y=height
  
  Wg = PEf - PEi 
  
5.4) Conservative and Non-conservative forces
 
 A force is conservative if the work it does on an object is indepent of the
 path it takes.  i.e., no friction.
 
 A non-conservative force leads to dissipation of mechanical energy, usually due
 to friction.
 
 
5.5) Conservation of mechanical energy

  KEi + PEi =  KEf + PEf

   Potential Energy Stored in a Spring
   
   Hooke's law
   
   PEs ≡ kx2
   
   where k = spring constant
  
5.6) Non-conservative forces and the Work-Kinetic Energy Theorem

  Wnc = (KEf + PEf) - (KEi + PEi)

5.7) Conservation of Energy in General

  Energy can never be created or destroyed.  Energy may be transformed from one 
  form to another, but the total energy of an isolated system is always 
  constant.  Therefore, the total energy of the Universe is constant.
  
5.8) Power
  _                     _
  P  = W/Δt = FΔs/Δt = Fv
  
  unit for power is the Watt, 1 W = 1 J/s = 1 kg m2/s3
  


Homework 4:
pp. 139 # 1
pp. 140 # 3, 4
pp. 141 # 1 
pp. 142 # 7, 17
pp. 144 # 41