The rain drop can run off and reach the ocean in a river. It can
evaporate and become a cloud again and rain again and again. The rain
drop can also be absorbed into the ground and end up being taken into a
plant and then be respired into the air to become a rain drop again. Or
the rain drop can sink into the earth and become part of an underground
aquifer and eventually flow into a river and into the ocean. One other
path would be for the rain drop to fall in the mountains and turn to
ice and end up as part of a glacier and eventually flow into the ocean
if it is in Alaska or somewhere that glaciers flow into the ocean.
When you are running in a race, one feedback mechanism that happens as you increase exercise and muscle activity is that, your heart rate also increases. Your heart rate increases because it needs to sustain the body's need of more energy to be supplied to the different parts of the body during an activity.
