Suppose a 136 kg manhole cover is launched 50 feet in the air. What is the speed of the manhole cover when it hits the ground on its descent, in m/s and mph? I converted 50 feet to 15.24 meters, but I do not know what equation to use here. I understand that acceleration due to gravity is 9.8m/s^2. I just don't know how to find the speed when I am only given acceleration due to gravity and distance/height.