Charge of uniform density 34 pC/m2 is distributed on a spherical surface of radius = 1.8 cm, and a second concentric spherical surface of radius = 4.7 cm carries a uniform charge density of 63 pC/m2. What is the magnitude of the electric field at a point 3 cm from the center of the two surfaces?

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