What is the hypothesis for force and fan carts

This is a classic physics problem that you can explore by using simple materials to build a low-friction cart with a removable motor and sail. The Fan Cart provides an elegant demonstration of action-reaction pairs described in Newton’s Third Law, and can also be used to demonstrate other aspects of force and motion.

The answer is water molecules are split.cellular respiration and photosynthesis are complement  reactions to each other. these are reverse reactions. in cellular respiration glucose and oxygen yield water and carbon dioxide. so, when respiration begins,  glucose molecules are split. in the opposite reaction - in photosynthesis, carbon dioxide and water yield glucose and oxygen. thus,  when respiration begins, water molecules are split.