Resources for Force Lab:
Rolling Resistance:
Rolling Resistance: Here is the general definition of rolling resistance from wiki. In this definition N (called the Normal Force) is the same as your weight. We will show this relationship to be true for chairs in general. When we determine the slope of the plot we are finding the coefficient of rolling resistance.
Energy Loss in Cars (courtesy of Tesla Motors) As you will note on the plot the energy loss due to the tires (rolling resistance) is a major part of the energy cost of driving a car below 15 m/s (30 mph). Also note that this energy loss is the same at all speeds which means it doesn't depend on speed.
Plotting in Science:
Here's a nice discussion of why we plot things in science. Actually making plots you may have learned in math class but that's different than understanding how we use this process in science.
This pdf document from Mr.Gilliland (high school science teacher) does a great job of describing the way we think about graphs in science.
For amusement only: Some people like to collect "bad" graphs. These are graphs that are labeled in such a way as to obscure (intentionally or otherwise) the meaning of the data or the actual absence of data. Here is a recent example with some explanation.