A solid disk of mass 1.45 kg and radius 25.0 cm is initially spinning counterclockwise (as viewed from above) at 15.5 revolutions per second on a massless and frictionless bearing. A second disk, of mass 1.05 kg and radius 12.5 cm is initially spinning clockwise about the same axis at 14.2 revolutions per second, is dropped on top of the first disk. Because there is friction between the disks, they quickly reach a common angular speed. What is their final angular speed, in revolutions per second

Transfer of electrons. hope it !

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