To find the velocity of the stone as it hits the water, we can use the equation for free fall motion:

v = gt

Where:

v is the final velocity (which is zero at the top and increases as the object falls)

g is the acceleration due to gravity (approximately 9.8 m/s² near the Earth's surface)

t is the time taken

In this case, the stone hits the water after 3.4 seconds, so we can substitute the values into the equation:

v = 9.8 m/s² * 3.4 s

v ≈ 33.32 m/s

Therefore, the velocity of the stone as it hits the water is approximately 33.32 m/s.