## From the Common Sense Problem Page

### Physical Reasoning

When baking cookies, after you prepare the cookie dough, you lightly spread flour over a large flat surface; then roll out the dough on the surface with a rolling pin; then cut out cookie shapes with a cookie cutter; then put the separated cookies separately onto a cookie sheet and bake.

Variants:
What happens if: You do not flour the surface? You use too much flour? You do not roll out the dough, but cut the cookies from the original mass? You roll out the dough but don't cut it? You cut the dough but don't separate the pieces?

What happens if the surface is covered with sand? Or covered with sandpaper? If the rolling pin has bumps? or cavities? or is square? If the cookie cutter does not fit within the dough? What happens if you use the rolling pin just in the middle of the dough and leave the edges alone? If, rather than roll, you pick up the rolling pin and press it down into the dough in various spots? Ordinarily the cutting part of the cookie cutter is a thin vertical wall above a simple closed curve in the plane; suppose it is not thin? or not vertical? or not closed? or a multiple curve? If the cuts with the cutter overlap one another?

Does the dough end up thinner or thicker if you exert more force on the rolling pin? If you roll it out more times? If you roll the pin faster or slower? Do you get more or fewer cookies if the dough is rolled thinner? If a larger cookie cutter is used? If there is more dough? If the cuts with the cutter are spread further apart?

What is the point of placing waxed paper on the surface? What happens if the above procedure is tried with a recipe for drop cookies? bar cookies? refrigerator cookies?

Contributed by
Leora Morgenstern (leora@steam.stanford.edu) , IBM T.J. Watson Research Center, U.S.A.
and
Ernie Davis( davise@cs.nyu.edu), New York University, U.S.A.
(18th September 1997)