A chemical reaction in the battery tries to maintain a constant potential (voltage) difference between the negative and positive terminal of the battery. Do your observations support this?

Yes

Explanation:

A chemical reaction maintains a constant voltage between the negative and positive terminals of a battery. Electrons are transferred from anode to cathode. As the reaction progresses, the voltage decreases continually until the reaction attains equilibrium and the voltage between the battery terminals becomes 'zero'. At this point, the battery is said to be dead because there will be no more flow of current between the terminals of the battery.

c because the action was the roller coaster reaches bottom of hill (action) reaction would be blood tends to drain away from head

hope this !

that would be because of both gravity and friction. so     c