Question

Sal is building a robot, if he puts a sphere on top of a cylinder. What would happen?

Answer 1

Something would have to hold the sphere in place or it would roll off the cylinder, but if it was in place it could be the head of the body.

Answer 2

the sphere would fall over or be unbalanced on the cylinder, it doesn't have a flat surface where it can be balanced.

(unless you use glue or stick the sphere onto it :P)