When we can get the Kinetic energy from this formula KE= 1/2 M V^2 and we can get the potential energy from this formula PE = M g H
we can set that the kinetic energy at the bottom of the fall equals the potential energy at the top so, KE = PE 1/2 MV^2 = M g H 1/2 V^2 = g H when V is the velocity, g is an acceleration of gravitational force and H is the height of the fall. ∴ v^2 = 2 * 9.8 * 8 = 156.8 ∴ v= √156.8 = 12.5 m/s