6. The largest airplane ever built is the Hughes H-4 Hercules flying boat. Its 97.5 m wingspan is still 9.1 m longer than the next largest plane
ever to be built. However, because it is made of birch (not spruce, as
its popular nickname-the Spruce Goose-would suggest), the mass
of the H-4 is 1.81 x 105 kg, considerably lighter than any other giant
plane. The H-4 was flown only once, over a distance of about 1.6 km. If
the maximum gravitational potential chergy associated with the H-4
was 3.78 x 107 J, how high did it fly?