Assume a toy car is rolling down an incline plane with all wheels rolling
freely (no wheels are sliding). Should I be making a distinction between
rolling and static friction? What is the direction of that friction? Is
it down the incline in the direction the car is moving or opposite the
direction the car is moving?
We had an interesting discussion about this problem today in our workshop
and I was interested in some new ideas. The discussion arose out of a
demonstration where a toy Tonka car was allowed to move down an
incline, first with the rear wheels taped so they would not move.
Then the front wheels were taped and the rear wheels were allowed to
rotate. When the rear wheels are taped, the car slides out of control
and falls off the incline but when the front wheels are taped to the
car, the toy car will ALWAYS slide straight down the incline.
Your ideas are welcome.
Lowell Herr
Project PHYSLab
The Catlin Gabel School
Portland, OR 97225