## Day 18 – Defining Physics Terms

Thurs Sept 26, 2013

Chemistry 1 – Sorry, I forgot to get good pictures or whiteboards today.  We spent class today discussing the 6 parts of the Mass and Change Lab.  Each small group presented their explaination and particle diagram model of what happened in the lab.  There were some interesting discussion points brought up, especially when mass was gained or lost.  How could that happen?  The liveliest discussions came from the burning steel wool station, but also the mass of ice melting into water.  One question that was posed was that wouldn’t the ice have more mass because it “traps” air inside the cube when it freezes?  When it melts the air would then be released.  Thoughts?

Physics 1 – We’ve been using Robots to study simple constant velocity 1D motion.  I intend to write  full regular blog post (bradwysocki.wordpress.com) on the details soon.  However, today we discussed the challenge given yesterday of having two robots start at different locations and end up at the same point at the same times.  Students then graphed what both robots motion looked like on one graph.  From this exercise the term Distance, Position, Speed and Velocity naturally arose.  I had to do a little injecting to get Displacement out there.  These 5 terms were easily defined, agreed upon, and understood as to why there are so many terms to describe motion by the students without the aid of any textbook, Google, or me just telling them that is the way it is.

Above you can see a couple of group’s graphs.  The one on the left first was labeled distance, but a student brought up the impossibility of “Joule” to travel 60 cm in 0 seconds.  The second group board shows an accurate distance vs. time graph of their motion, but it didn’t really model what actually happened.  I modified it as we discussed by drawing the graph above, and as a class we decided using the term position was more useful than distance.  We also see how it was still traveling 80 cm, but in a negative direction.  This brought up distance vs. displacement and speed vs. velocity.  Physics WIN!

Chemistry 2 – We finished analyzing and calculating an unknown concentration of a solution using the data obtained from graphing Absorbance of a solution vs. known Concentration.  We also worked on a practice set of problems dealing with the concept of Molarity.