MHB Water Displacement Volume question

[akarikairi]

Sorry if this is the wrong category for this.

I am mostly confused about this question because I thought that displaced water WAS the volume of any given object. I'm confused by the reasoning of the actual answer for this. Is there something I'm missing here?

View attachment 4707

 

[Greg]

The difference between the height of water when the bridge is immersed minus the height of the water when the bridge is removed is 0.02m. This is not the volume of the bridge; you need to calculate the volume of water with a height of 0.02, a length of 3.5m and a width of 2m:

$$3.5\text m\times2\text m\times0.02\text m=0.14\text m^3$$

This is the volume of the bridge.

 

[akarikairi]

Ah ok, that makes sense. I see it now. Thanks for clearing that up :)