A diver of

We can use the equation for conservation of energy to calculate the velocity of the diver as he hits the water:

E = U_i +K_i = U_f + K_f

Cancel out initial kinetic and final potential energies, and plug in our expressions:

Cancel out mass and rearranging for final velocity:

We know that the diver then decelerates from this velocity to zero in 0.8 seconds, so we can calculate the acceleration:

Newton's second law to calculate the force on the diver:

F = ma = (50) (25 m/s²) = 1250N