10-10-08

__ The Physics Journalist __ On October 10, 2008 Mr. Manning’s Physics class continued to learn despite Senior Skip Day. It was set out from the very beginning that students would: -answer a Daily Question (details later) -prepare for a quiz on Tuesday on XT-Graphs -Finish the Video Lab (XT Graphs of Objects in Freefall, pg 13.) -complete a worksheet on descriptions of XT- Graphs The daily question asked students to describe an XT Graph. When describing an XT-Graph, one should answer the questions: -Where do you start? (Initial Position) -How must you move? (Speed) -In which direction must you move? (Direction) The homework assignment (XT-Graph Descriptions, pg. 15.) required answers to be in complete sentences. Failing to do so would result in dire consequences according to Mr. Manning. A fellow classmate, Aura Tremellen said that she disliked the homework, deeming it to be “busy work”. -It is important to understand that straight lines on an XT-Graph denote a constant speed. Curved lines denote an increasing or decreasing speed. When viewing curved lines on an XT-Graph, it is often difficult to understand the speed that the line illustrates. Basically, the viewer of the graph wants to pay close attention to the slope of the line. If the slope of the line is initially fairly close to zero and then gradually becomes farther away from zero (steeper) the speed is increasing. If the slope of the line is initially far away from zero or “steep” and then gradually becomes closer to zero the speed is decreasing.

Here is an example of an XT-Graph. The initial position of the line is at the origin or reference point. The speed is increasing because the line becomes steeper. The line has a positive direction.