Linear velocity
This term a decision was made to start zero meters at the LRC. This puts 30 meters at the entrance to the faculty building. Zero off of LRC plays well with acceleration from rest next week.
Keeping this coordinate grid may invert the parabola on deceleration and acceleration a week from Wednesday. The downside would be that d₀ would no longer be zero. Another impact would be the likely generation of imaginary roots as the parabola wouldn't teach the x-axis. This would be confusing at best. Better to start at t=0, d=0 with d₀ = 0.
The thirty meter RipStik run.
Despite the first 12 meters having a slope, velocity was fairly consistent. Start was up by the solar panel electrical closet with a ninety degree turn in to the run.
1.96 meters per second is a reasonable velocity, in line with historic values.
Wednesday's walking exercise used the existing 30 meters off of the LRC. The goals were for the students to gain further familiarity with metric system measures, learn to use the stopwatches including memory mode, and to measure their walking speed.
Meramy on the right
Thursday I decided the slope might be problematic as a starting point for rolling the ball. I feared an acceleration might creep in on the slope. In retrospect I am not so sure that would be an issue. There is substantial ground friction, the slope might overcome that.
This decision moved the zero meter mark just west of the location in prior terms.
Without a post for affixing the tape measure, the tape had to start from the LRC zero post. This meant the numbers from the day before were invalid. Nine meters was the new zero. This put the 1.5 meter mark at 13.5 meters. Subsequent marks were similarly offset. Perhaps a roll start on the slope would have eliminated the need to renumber.
The slow velocities were done using 1.5 meter spacing of the timing marks. Moderate velocity was done using three meter spacing. Fast was done using 4.5 meter marks. Different colors of sidewalk chalk highlighted the different timing spans.
At eight o'clock all rolls were ball rolls. Some students chose rolls for moderate velocity and fast velocity that were barely distinguishable. The moderate and fast are reasonably separated in the above data. The slow ball, at 2.13 m/s, is twice the slow speed of a RipStick. Perhaps the slow speed should be done with RipStik - that is the speed for which the ball rolls off course most often. The fast ball was 5.25 m/s, well above the speeds ever seen on the RipStik.
At 11:00 the slow and fast velocities were done with the ball.
The moderate velocity was done with the RipStik. The slow ball in the above data is a more leisurely 1.10 m/s. The RipStik turned in a velocity of 1.73 m/s, the typical cruise speed for gentle swizzles. The fast ball came in 4.53 m/s.
Prior to the 11:00 section, students were asked to predict the time versus distance graphs.
Given that the students had seen a time versus distance graph at a constant velocity on Monday, and then did this exercise again on Wednesday, and that at least two-thirds of the students had college level algebra or higher, this prediction should have been within reach for the students. Yet only two student produced the correct graph.
The 11:00 board included echoing of the predictions. The left board had only the laboratory report structure. In both sections a sample laboratory report was displayed.
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