Physical science RipStik and Linear motion laboratory
To demonstrate linear motion while retaining some modicum of attention span from my social media saturated students, I rode a RipStik along the sidewalk in front of the laboratory. The activity is built around the linear relationship between time and distance for an object moving at a constant velocity. Thus my goal was to maintain a constant velocity over the 32.2 meter distance.
In prior terms I have started the timing one post earlier, resulting in the coverage of 36.8 meters. I wanted to maintain a slightly slower, steadier speed this summer. I used the first two posts to establish a slightly slower speed and then worked to maintain that speed. Establishing a constant speed on a RipStik is roughly equivalent to maintaining a constant swizzle frequency.
The times were obtained by using a stopwatch to time the passing of pillars that are 4.6 meters apart.
The time versus distance data has a linear regression slope of 1.27 m/s. In January 2011 the linear regression was 1.43 m/s, thus I was moving slower this summer than last spring.
The data was gathered in later one third of the period, the students are given as homework the task of plotting the data, determining the slope and thus the speed of the RipStik. The students are not asked to find the pillar-to-pillar velocities and accelerations, although that would be certainly be appropriate for a physics class. The class is a physical science class that is a survey of the physical sciences from mechanics to cosmology and all points inbetween.
Due to rain, laboratory 02 was revamped on the fly and performed in the classroom using marbles. The procedure used was essentially identical to the outdoor ball rolling procedure. When released from higher locations on the ruler ramp, the marbles ran out of table before six seconds were up.
The ramp set-up used a block and ruler.
Marbles were rolled. a marble in motion can be seen just pass Maimai's hand. Maimai is marking the location of the marble at one second using a Post-It note.
Notes for the location of the marble at four, five, and six seconds. Each table was a group. Lab has 16 students, thus the groups were five, five, and six students.
Lewis and Lavanaleen review their data. The following is sample data gathered during the laboratory. Note that for launches farther up the ramp the marble ran out of table before six seconds had elapsed.
The marbles slowed down a good deal more than I expected over the short runs.
That the marbles are slowing down can be more clearly seen by using a power function for the regression.
When laboratory 02 was done in a parking lot there were indications that reaction time issues may have led starting the stopwatch late. This results in the first second starting after the ball had left the ramp. The extra distance shows up as an erroneously high velocity for the first second. This may be a factor in what otherwise appears to be a sudden drop in speed after the first second.
Both the outdoor and indoor variations of this laboratory have issues of speed loss for the ball or marble. I suppose an alternative laboratory that might avoid the issue of loss of velocity would be something akin to riding a RipStik at five different speeds.
In prior terms I have started the timing one post earlier, resulting in the coverage of 36.8 meters. I wanted to maintain a slightly slower, steadier speed this summer. I used the first two posts to establish a slightly slower speed and then worked to maintain that speed. Establishing a constant speed on a RipStik is roughly equivalent to maintaining a constant swizzle frequency.
| time (s) | distance (m) |
| 0 | 0 |
| 3.81 | 4.6 |
| 7.79 | 9.2 |
| 11.32 | 13.8 |
| 14.87 | 18.4 |
| 18.59 | 23 |
| 21.94 | 27.6 |
| 25.22 | 32.2 |
The times were obtained by using a stopwatch to time the passing of pillars that are 4.6 meters apart.
Click on the chart to view a clearer image
The data was gathered in later one third of the period, the students are given as homework the task of plotting the data, determining the slope and thus the speed of the RipStik. The students are not asked to find the pillar-to-pillar velocities and accelerations, although that would be certainly be appropriate for a physics class. The class is a physical science class that is a survey of the physical sciences from mechanics to cosmology and all points inbetween.
Due to rain, laboratory 02 was revamped on the fly and performed in the classroom using marbles. The procedure used was essentially identical to the outdoor ball rolling procedure. When released from higher locations on the ruler ramp, the marbles ran out of table before six seconds were up.
| time (s) | Bottom of ramp (cm) | Quarter | Half-way up (cm) | Three-quarters (cm) | Top of ramp (cm) |
| 0 | 0 | 0 | 0 | 0 | 0 |
| 1 | 0 | 112 | 140 | 156 | 190 |
| 2 | 0 | 164 | 207 | 231 | 300 |
| 3 | 0 | 211 | 281 | 324 | |
| 4 | 0 | 259 | 306 | ||
| 5 | 0 | 334 | |||
| 6 | 0 |
The marbles slowed down a good deal more than I expected over the short runs.
That the marbles are slowing down can be more clearly seen by using a power function for the regression.
When laboratory 02 was done in a parking lot there were indications that reaction time issues may have led starting the stopwatch late. This results in the first second starting after the ball had left the ramp. The extra distance shows up as an erroneously high velocity for the first second. This may be a factor in what otherwise appears to be a sudden drop in speed after the first second.
Both the outdoor and indoor variations of this laboratory have issues of speed loss for the ball or marble. I suppose an alternative laboratory that might avoid the issue of loss of velocity would be something akin to riding a RipStik at five different speeds.
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