RipStik Deceleration

Acceleration is introduced by riding a RipStik up a slope while decelerating, turning around at the top of the slope, and then accelerating back downslope. Posts along the covered walkway provide timing points. Prior to going outside on Monday I sketched a graph on the board of what a time versus distance graph should look like if I rode with decreasing speed and then turn around and ride with increasing speed. The result is a roughly parabolic prediction. Note that negative velocity on a graph was also covered on Monday.

time (s) split dist (cm) distance (cm) velocity (cm/s) acceleration (cm/s²)
0 0 0

0.97 306 306 315.46
2.13 305 611 262.93 -45.29 Avg Acc
3.69 307 918 196.79 -42.39 -44
6.72 316 1234 104.29 -30.53 -39
10 -316 918 -96.34 -61.17 -45
11.82 -307 611 -168.68 -39.75 -44
13.07 -305 306 -244.00 -60.25 -47
14.69 -306 0 -188.89 34.02 -35

Graphing the time versus the distance (third column) provides speed information from the slope. The students were given this as homework. 

On Wednesday I asked the students if they got the shape I predicted, which they did. Then I spent Wednesday showing them that a change in speed per unit time can be calculated, generating what I explained would be called acceleration. The students had the table above and the graph on a handout as reference.

I built from the slope of the above is the velocity to the slope of the velocity versus time is the acceleration.

I then drew attention to the acceleration always being negative until the final post and what that meant, negative with a slope of zero.

The handout also had the above chart. This then builds into measuring the acceleration of gravity.


Popular posts from this blog

Box and whisker plots in Google Sheets

Areca catechu leaf sheaf petiole plates

Setting up a boxplot chart in Google Sheets with multiple boxplots on a single chart