The velocity, $V$, of an object, in feet per second, after it has fallen a distance, $h$, in feet, can be determined by the formula $V=\sqrt{64.4 h}$. A pile driver is a large mass that is used as a hammer to drive pilings into soft earth to support a building or other structure. With what velocity will the hammer hit the piling if it falls from
a) 20 feet above the top of the piling?
b) 40 feet above the top of the piling?