A stone of mass 
is thrown horizontally from the top of a cliff with a speed of 
, as illustrated in the figure below.
The initial height of the stone above the level of the sea is 
. Air resistance may be neglected.
Calculate the change in gravitational potential energy of the stone as a result of falling through .
Calculate the total kinetic energy of the stone as it reaches the sea.
Use your answer in (a)(ii) to show that the speed of the stone as it hits the water is approximately 
.
.
.
