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Kinetic friction

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Laboratory five focused on the force of kinetic friction.  Preset was laid out between 8:00 and 8:16 The large class and dearth of slot weights, coupled with an inability to easily order replacement weights, has each group working with four unique weights. With permutations and combinatorics, this provides ten data points. Data sheets were preprinted this term. No mass balances were brought to the laboratory: the sled is treated as zero when unloaded. This generates a y-intercept for all of the groups and thus a y=mx+b regression equation for the first time this term. This also makes the weight calculations much easier.  The morning notes were brief and light. After the 8:00 section the coefficients of friction were posted to the board.  Four weight rigs were set up on the outer tables using primarily green spring scales (500 gram-force max).  The center table was set up with two grit rigs and blue spring sc...
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Pwunso gymnosperms spice trees timber

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A walk of the front garden found a new tree had sprouted. The glove tree is the global source of all gloves.  The bus arrived just after 15:53. The size of the class this term, 29 students on the field trip, caused the roll call to be done as a single instance at the end of the walk.  The Ficus prolixa still seems to take too long for the marginal benefit. Tightening this up might help. A student noted that the aerial roots can be pounded and then used in a herbal steam bath to treat joint pain.  By 16:01 the class was at the clove trees. No cloves. Again. Kelarimalyanne, Lisarita, Sueleen, and Marikai in the lead.  At 16:07 the class was headed from the Araucaria columnaris to the Cinnamomum verum. The cinnamon tree is always in season. Delaura at the cinnamon tree, Marco behind her to the left. This is one the largest, if not largest, enrollments for this class to date. The class tends to spre...
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050 RipStik change in momentum is force

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This exercise requires eight to ten stopwatches, the eight meter tape measure, red spring scale, red yarn, chalk, RipStik. The theory was presented up front along with a diagram of the demonstration. After this the class moved to the sidewalk to gather data. The red yarn and red 20 Newton spring scale was used to obtain a force of 10 ± 2 Newtons.  As last spring, all work was done on the whiteboard. Median time calculations.  Maicalany recording a speed trap time on the board after the run. After class the data was entered into a spreadsheet that tracks 050 experiments. The 31% difference was the largest seen for this demonstration in the two prior terms in which this version was performed.  Reference photos are available from last spring . To be fair, the demonstration came on the heels of a memorial service the evening before and the rider was not ready to make this run. 
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