Rivers respond to gravity, and flow downhill or down any slope. The current (flowing water) will react according to the slope down which it is moving.
Gravity
Gravity
Gravity, rivers flow downhill
Actually many rivers run north in North America. Water has no sense of direction. If flows downhill by gravity. Most rivers east of the Rocky Mountains do flow in a southerly direction because the elevation is lower to the south and they are flowing toward the Gulf of Mexico. Source: Riverlorian.com
it slows down because first it rushes down from mountain and then slows down right at the end when it goes into the sea/ocean/lake.
Rivers flow down.
No. In the mountains, gravity makes the rivers flow faster. Lowland rivers are slower than mountain rivers.
As with all rivers - Gravity.
Gravity, not gods cause rivers to flow. Most rivers in the northern parts of continents flow from south to north.
Gravity
No because hydroelectricity is renewable (meaning that it isn't in a limited supply). Gravity from the earth, sun, and moon cause rivers to flow and since gravity will never end, rivers will always run and be available for the making of hydroelectricity.