A cannonball is fired horizontally from the top of a cliff. The cannon is at height H = 50 m above ground level, and the ball is fired with initial horizontal speed v_0. Assume acceleration due to gravity to be g = 9.80 m/s^2. Given that the projectile lands at a distance D = 100 m from the cliff, as shown in the figure, find the initial speed of the projectile, v_0.