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Float and Sink
Imagine that you are having sunflower seeds for a snack and that
they spill. The seeds fall onto gravel where they are hard to see. How
could you separate this mixture of seeds and gravel? Just scoop up
the seeds and gravel and drop them into a bowl of water. The pieces
of rock (gravel) will
sink
. The sunflower seeds will
float
.
Why do the seeds float and the bits of rock sink? Some might
say it is because rocks are heavier than sunflower seeds. But that
wouldn’t be true.
Think about this. A piece of gravel on one side of a balance and
a seed on the other side have the same mass. Each has a mass of
exactly 0.1 gram (g).
A small piece of gravel and a large sunflower seed
have the same mass.
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