A rectangular deep tank is 22m x 20m x10m. Above the crown of the tank is a rectangular trunkway 0.2m high, 5m long and 4m wide. Find the thrust on the tank lid when the tank is pressed up with SW to a head of 2.64m above the crown of the tank.

Rectangular deep tank  = 22m x 20m x10m
Trunk way = (5m x 4m x 0.2m)
Pressure = (depth x density)
              = (2.64m – 0.2) x1.025

Since , Depth is (2.64m – 0.2 )  and we have the calculate the thrust   act  on the trunkway and the water level above the trunkway will act as thrust )

If this trunkway would have been placed inside the tank then the depth will be   (10m + 2.64m – 0.2/2m ).

Area of the trunkway = (L X B)
                                = 4×5
                                 =20 m²

Thrust experienced = (P X  A)
                           = (2.501 x 20 )
                          = 50.02tonnes.