Perth, May 7 2020
Day 46 of #Covid19 #socialdistance
Today we explored the concepts of capillarity and of communicating vessels while building a colourful triangle of cups.
We started with filling three cups of water and putting some drops of red and blue food dyes and yellow water colour. We mixed with spoons. Then we made 6 bridges of paper towels and we made a triangle with 6 cups, 3 of which empty and placed in between two with the coloured solution, as in this picture.
Due to capillarity - water able to climb up the paper towel - and to the communicating vessel principle - the liquid into communicating vessels would get to the same level in each vessel - the liquid quickly went to fill the three empty cups until they all reached the same level. It took less than a couple of hours, but we were drawing in the meantime so we didn't notice exactly when the experiment was done.
I'm not sure exactly what happened, it may be the kind of paper towel OR the kind of colours OR both: the colour travelled along the bridge a lot more slow than water, so to make the orange, green and purple solutions I had to swap the position of the bridge. This usually doe not happen, so I wander what we did wrong...
Anyway, it was good fun seeing empty cups getting filled with water and we also learnt that:
blue+red=purple
blue+yellow=green
red+yellow=orange
And the cups all together make the rainbow!
Learning outcomes:
principles of fluid dynamics
primary colours in painting
Materials: as in picture