I first worked out the buoyant force using rho = 1000, g = 9.8 and V = 1. (this gives Fb = 9800)
I then worked out Fg of the tank (5 x 9.8 = 49)
Then I used Fnet = Fb - Fg - T = 0 to work out tension as 9751.
I thought the work done would be the work done by tension (9751 x 50.4), but I'm not...