Hey there!

this is most likely solved by a series, possibly a power series.
We are given unlimited number of identical, very thin dominoes. The length of a domino is 2 cm and it's mass is neglegable (10 ^ -4314 gram per domino).
Suppose we stack them(assume we are infinitely powerful), one on top of the other, so that the stack advances horizontally in one direction because each is offset a little. the top domino is offset 1cm, and as we move down the stack they are offset progressively less from each other so as to keep the center of gravity. the stack is kept stable only by gravity.
1) show that the stack can advance infinite distance. HINT: numerate the dominoes in a stack from the top. Note that a stack of two dominoes can advance 1cm since the center of the first domino should be above the edge of the second domino. Place the third domino underneath the first two dominoes so that the edge of the third domino is below the center of the stack of the two dominoes that has been built already.