The beautiful multnomah falls in oregon are approximately 206m high. if the columbia river is flowing horizontally at 2.90m/s just before going over the falls, what is the overall velocity of the water when it hits the bottom?

The overall velocity of the water when it hits the bottom is:

Explanation:

Use the law of conservation of energy.

Call it instant [1] to the moment when the water is just before reaching the falls.

At this moment its height h is 206 meters and its velocity  horizontally is m/s.

At the instant [1] the water has gravitational power energy

The water also has kinetic energy Ek.

Then the Total E1 energy is:

In the instant [2] the water is within an instant of touching the ground. At this point it only has kinetic energy, since the height h = 0. However at time [2] the water has maximum final velocity

So:

As the energy is conserved then

Now we solve for .

d.7.5cm is your answer