English: Capillary water flow in a brick that ...

Capillary water flow in a brick that is in contact with water at the bottom. From the weight increase, the estimated porosity is 25%. (Photo credit: Wikipedia)

Paper Towels and Water.

How can you make water defy gravity by rising up instead of pouring down?

Materials:

  • 3 paper towels (can also use cloth rags)
  • 6 glasses the same size
  • 2 small bowls (or any two things the same size to put a glass on top of)
  • Measuring glass
  • Water

Instructions:

  • Twist the paper towel, starting at one corner, until the entire towel is lightly twisted into a rope, corner to corner.
  • Set up the glasses in three rows:
    • 2 glasses side-by-side
    • 2 glasses, with the left one on top of an overturned bowl
    • 2 glasses, with the right one on top of an overturned bowl
    • Fill the left glass in each pair ¾ full with water
    • Put one paper towel rope in each pair of glasses, with one end in each glass.

What Should Happen?

  • After 10 minutes:
    • Water in the even pair of glasses will have traveled up the rope to a mid-way point between the two glasses
    • Water in the high left glass will have traveled almost to the top of the rope in that glass
    • Water in the high right glass will have traveled over the rim of the glass into the portion over the edge of the lower glass
  • After 30 minutes:
    • Water in the even glasses will have traveled to about 3 inches from the bottom of the rope in the empty glass
    • Water in the high left glass will have traveled to within an inch from the bottow of the rope in the empty glass
    • Water in the high right glass will have traveled over the lip of the empty glass

After about an hour, all the water from the left glass in the even pair will have drained into the right glass.

Why Does This Happen?

The scientific principle we are seeing is called capillary action, also known as wicking.

Several conditions must be present for capillary action, water defying gravity to climb up the paper towel rope, to work.

Narrow space.

The space the water travels in must be narrow, like our twisted rope.

You see the same effect on paint brush bristles, when the paint draws up on the bristles.

Surface tension.

The water has to have something to cling to, to use surface tension. It doesn’t just rise into the air.

Optional

What would happen if you used another liquid, instead of water?

What would happen if you added salt or sugar or dirt to the water? Would it rise as fast?

How Do You See This in Real Life?

Capillary action is how tears naturally wash out our eyes.

It is how water disburses in dry soil.

It is how wicking fabrics drain sweat away from our skin to keep us dry, especially in work-out clothes.

Thanks to sciencekids.co.nz for this activity.

 

Carol Covin, Granny-Guru

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandmothers

http://newgrandmas.com

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