HON 164: The Week beginning Jan. 22

• Homework:
  
  Read and summarize in your own words the second chapter of Voodoo Science (Robert Park). The summary should be a one-page Word doucment, double-spaced, normal default margins.
  
  Due: Jan. 29
  
  Read pp. 4 - 16 of The Great Physicists from Galileo to Einstein (George Gamow). This material is mainly on Archimedes.
  
  
• Monday:
  
  We discussed the concept of a weighted average. For instance, we considered calculating a student's grade for a course with the following components and weights
  
  

  	Midterm:	25%	90
  	Final:	25%	92
  	Paper:	15%	88
  	Homework:	15%	99
  	Labs:	15%	97
  	Class:	5%	95

  
  
  Grade = (.25)(90) + (.25)(92) + (.15)(88) + (.15)(99) + (.15)(97) + (.05)(95) = 92.85
  
  We introduced the idea of the "center of mass," which is also an example of a weighted average.  We then proceeded to examine the geometric argument for the center-of-mass given in the following handout.
  
  Center of Mass and the Law of the Lever
  
  
• Wednesday:
  
  We considered that if the two masses were part of a lever system that the fulcrum must be positioned at the center-of-mass to balance the system. Furthermore, we talked about the effect of changing the coordinate system in the center-of-mass formula (what changes and what stays the same). Then we chose the origin (0) of our coordinate system to be at the center-of-mass (also now the fulcrum). The positions of the masses are now associated with lever arms allowing us to connect the center-of-mass result to the law of the lever result. We connected the law of the lever to the experiment performed last week, namely the reciprocal relationship we found between force and lever arm for the balanced lever system. We consider that a lever could be used to multiply the effect of our force (as in a crowbar). However, an argument using similar triangles showed that the work done (roughly, force times distance) was not multiplied but remained the same. This is an example of the principle of conservation of energy that was mentioned in the first chapter of the Voodoo Science book.
  
  We moved onto another result associated with Archimedes, namely the determination of density obtained by having an object displace water. A density is mass divided by volume. We mentioned some units for volume such as liter and meter³. We looked at a conversion from one to the other, for example, the following:
  
  0.6 liters = (0.6 liters)* (1000 milliliters/1 liter) * (1 cm³/1 milliliter) * (m/100 cm)³ = 0.0006 m³
  
  We mentioned that the original definition of a gram was the mass of a milliliter of water, thus making the density of water 1 g/ml.
  
  
• Friday:
  
  Buoyancy and density
  
  Note that starting Monday we will meet in Olney 323.
  
  Due: Feb. 2