Velocity

Day three is week two in summer session physical science. And week two is velocity. After a note on screen capturing graphs to not cut off the bottom of the graph, the students were orally asked what a time versus distance graph would look like for an object moving at an unchanging speed. 

Then the class adjourned to the sidewalk where a 30 meter RipStik run was done. 

The newer stopwatch with timing to a thousandth of a second was used. That third decimal place is actually quite meaningless. 

This term marked a return to the sidewalk on a sunny day. Spring term the class used the vacant student center building. Prior to going to the sidewalk the students were asked to sketch what would be the result on the time versus distance graph for three ball speeds. About half of the students made a correct sketch. The most common misconception was a single line where different segments of the line corresponded to different speeds. 

The ball pump has failed so the four square ball was seriously under inflated. 

Jenry-Thor pitches a fast ball

As a backup plan the blue ball, purchased for the Malem Move-Out festival, was kept as a back-up. A quartering headwind was coming across the sidewalk with a left-to-right component. The strange result of the under inflated ball was that the ball tracked more consistently straight than in any prior term. The downside was stronger signs of loss of velocity to friction. But then the ball was very under inflated. Rolling was not its strong suite. But resistance to the crosswind was an apparent result.

The start was again done from the LRC - the slope offsets friction rather nicely. The slow ball rolls were done on 1.5 meter marks, the medium speed ball was done on 3 meter marks, and the fast ball was done on 6 meter marks.

During the ball rolling a meninrahn headed up the sidewalk and then stopped, curling up a foot or so away from where I was rolling the ball. The meninrahn remained there for a number of rolls. I took care not to hit the visitor and ensured that returned ball did not disturb our guest. 

A student walking up the sidewalk was headed to pass on my right. I pointed out the visitor explaining that perhaps this was a Dipwinpahpa, maybe an ancestor, who was stopping by to visit. After perhaps ten or fifteen minutes, our guest headed up the sidewalk and disappeared.