Afixed, single pulley that is used to lift a block does which one of the following? . a.. doubles the force required to lift the block. b.. decreases the force required to lift the block. c.. makes the block easier to lift by changing the direction of the force needed to lift it. d.. decreases the force required and changes the direction of the force required.

A fixed single pulley can't affect the forces. It only changes their directions.

W= fd
where f is an applied force and d is the distance over which it is applied. when a parachuting skydiver is at constant velocity, he is experiencing "terminal velocity", the point at which his acceleration down is canceled out by air resistance. that means that the resisting force of the air is equal to his weight, but in the opposite direction. with this, we can solve for the work done by the force.
w = fd
w = (92.0)(9.81 m/s^2) (325)
w= 2.93 x 10^5 j
the value for work in this case is positive because it is pushing up on the skydiver, who has a downward force of gravity.
therefore the answer is 2.93 x 10^5 j