Mechanics Help Please

1: The retaining wall of a storage pond is 12m wide by 10m high and holds back water at a depth of 8.5m. Calculate the resultant thrust on the wall, due to the water and the overturning moment on the wall. Take the density of water as 1000 kg/m^-3

2: A filter net is held across the inlet to the pond on a cylindrical boom of 400mm diameter by 4m length and is designed to remain immersed below the surface of the water. Determine the required up-thrust of the water, for the boom to remain immersed just below the surface.

3: The inlet to a fuel supply pipe is to have a mass flow rate of 525 kg/m^-1 and the maximum input flow velocity is to be held at 1.4 ms^-1. The pipe tapers to give an output flow of 5ms^-1. Assuming that the flow is incompressible and taking the density of fuel as 780 kg/m^-3 , determine the inlet and outlet diameters of the pipe, in mm.