I have made these measurements of kinetic friction force vs normal force:
I want to measure the coefficient of friction as the slope of the line. Unfortunately the line does not pass through $(0,0)$. If I force the intercept to zero I get a quite different coefficient of friction ($0.6$). I wonder if I should:
- Just use the slope and ignore that the line doesn't go through $(0,0)$
- Force the line through $(0,0)$
- Remove the two outer points since they are the most problematic.
- Remove the two outer points and force the line through $(0,0)$
I have no opportunity to redo the experiment so I have to work with what I got. What would be the correct approach?
EDIT: This is a school project and I'm the teacher.