please help as im confused on a certain question?

[dubberz25]

A water storage tank measures 2m x 1.5m x 2m and contains water up to a depth of 1.6m. Given that the pressure exerted by 1m2 of water is 9.81 kN / m2, which of the following calculations shows how the total pressure exerted on the base of the tank should be calculated?

a: 9.81 kN / m2 x 1.6
b: 1.6m x 9.81 kN / m2 x2m x 1.5m
c: 2m x 1.5m x 2m x9.81 kN / /m2
d: 2m x 1.5m x 9.81 kN / m2

 

[Alanka]

It is confusing isn't it!

The pressure exerted by water at the bottom of a vessel depends ONLY on the depth, not the volume or any other tank dimensions. So the pressure at the bottom of a 1m long vertical 15mm pipe full of water is exactly the same as the pressure at the bottom of a swimming pool at the 1m end: that is 9.81kN/m2 (9.81kPa)

1 metre of water depth exerts a pressure of 9.81kN/m2 (9.81kPa, about 0.1bar). So 1.6m depth exerts a pressure of 1.6 x 9.81kN/m2 = 15.70kN/m2 (15.70kPa).

So your first calculation is the correct one!

(A rough guide is that 1 atmosphere, i.e. 1 bar, or 100kPa, equals about 10m of water head.)