The rock strike the water with the speed of 15.78 m/sec.
The speed by which rock hit the water is calculated by the formula
v=[tex] \sqrt{2gh} [/tex]
v=[tex] \sqrt{2*9.8*12.7} [/tex]
v=15.78 m/sec
Hence, the rock strike the water with the speed of 15.78 m/sec.
