 CHAR: While discussing a workers fall from the roof of a  construction site, Grissom states that terminal velocity is 9.8  meters per second squared. That is actually the acceleration of a  falling object due to gravity. Terminal velocity of a falling human  body (a skydiver, say) is about 54 meters per second. To reach  terminal velocity, the body must fall almost 600m. By comparison,  the Sears Tower is only 442m tall.