Calculate the R-value of a thermal window made of two single panes of glass each 0.100 in. thick and separated by a 0.325-in. air space. (Take the R-value of a 3.5 in. air space to be 1.01 ft2 · °F · h/Btu, and the R-value for 0.100 in. thick glass to be 0.712 ft2 · °F · h/Btu.) (b) By what factor is the transfer of energy by heat through the window reduced by using the thermal window instead of the single-pane window? Include the contributions of inside and outside stagnant air layers.

Letter a, because when there are unlike charges they will always attract to each other.

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