00:01
Question 80 gives us three containers of water, which we're just going to draw out now.
00:10
And they're pretty much identical, apart from the situation that's going on in them.
00:16
In a, we have a floating block of wood.
00:21
In b, we have a floating block of wood with an extra mass on top of it.
00:28
And c is just filled with water.
00:32
And the key to this question is that the water levels, although it doesn't necessarily look like it in my drawings, should be considered to be exactly the same.
00:46
And the question then asks us, three identical containers, as shown in the figure, are open to the air and filled with water to the same level.
00:54
A block of wood floats in container a, identical block of wood floats in container b, supporting a small lead weight, and container c holds only water, rank the three containers in order of increasing weight of water they contain, and indicate ties were appropriate.
01:12
And we just need to consider archimedes ' principle.
01:17
So the containers are filled to the same level.
01:20
But less water is needed for container a than c, because the wood displaces some water.
01:27
So wood displaces some water...