When you use a paper towel to clean up spilled water, have you
ever noticed how the water seems to be taken up by the towel? Small openings in
the towel attract the water molecules. This is a force called capillary
attraction, and it pulls the water into the towel. If you hold the paper towel
vertically in a cup of water, you can see the water climb upward.
How high can you get the water to climb? Can you use this as a
kind of “water ladder” to raise water to a higher level without a pump? This
activity will help you explore these ideas.
Water can certainly move in
mysterious ways, get the water from one cup to make its way up hill and back
down into a second empty cup with the help of paper towels and an interesting
scientific process.
Instructions:
- Twist a couple of pieces of
paper towel together until it forms something that looks a little like a
piece of rope, this will be the 'wick' that will absorb and transfer the
water (a bit like the wick on a candle transferring the wax to the flame).
- Place one end of the paper
towels into the glass filled with water and the other into the empty
glass.
- Watch what happens (this
experiment takes a little bit of patience).
What you'll need:
- A glass of water
- An empty glass
- Some paper towels
What's happening?
Your paper towel rope (or wick) starts getting wet, after a few minutes
you will notice that the empty glass is starting to fill with water, it keeps
filling until there is an even amount of water in each glass, how does this
happen?
This process is called 'capillary action', the water uses this process
to move along the tiny gaps in the fibre of the paper towels. It occurs due to
the adhesive force between the water and the paper towel being stronger than
the cohesive forces inside the water itself. This process can also be seen in
plants where moisture travels from the roots to the rest of the plant.
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