Rolling balls and linear relationships

Physical science laboratory two was revised spring 2010 to include five different rolling ball speeds including a stationary ball. Coupled with a Monday RipStik time versus distance data gathering activity that led to a linear regression homework, the week now builds solidly on the concept of linear regressions introduced in the density lab the week before. The use of five balls speeds leading to five linear regressions provides a good basis for a discussion of how slope relates to velocity.

Ceasar releases the ball from the top of the ramp in an early morning run.

The roll from a quarter ramp was done by Ceasar and I only. I had broken up a branch of Albizia lebbeck and was using the pieces as timing marks while chasing the ball. Thus when the rest of the class rolled in between 0815 and 0820, the procedure of using sticks was was already in place.

As Loioshi calls out the seconds, Anna Belle leans in to place her stick. Evelyn waits for the two second mark to be called by Loioshi. Senioleen awaits the three second mark while Norma shifts left in anticipation of the four second location.
The above procedure ensures that the time is the independent variable while distance is the dependent variable. The traditional alternative records the time to a set of fixed distances. This should then be plotted with distance on the x-axis and time on the y-axis as the distance is being chosen first and then the time is being measured. That would, however, yield pace not speed. Some instructors go ahead and plot time on the x-axis and distance on the y-axis, but this then leads to bemuddlement of the concept of independent and dependent variables.

Angelo "throws down" on the five second mark in the 1100 section.

Loioshi enters the data into OpenOffice.org 3.2 running on Ubuntu 10.04 in the science computer laboratory. The course has a mathematical focus on linear equations and predictability; a writing focus on grammar, vocabulary, organization, and cohesion; and a technical focus on using spreadsheets and word processing software to produce reports that integrate tables and charts with text in a formal report format.