This week has been a week of exploring and experiments! One of the topics we have been exploring in depth is surface tension and the Floating Paperclip has been a favourite of the week. Izzy has had so much fun with this experiment that I actually lost count of how many times we did it over the course of two days!
Surface tension is the tension of the “skin” on top of a liquid. Water molecules hold on tight together which form the skin and allow things that are denser than water (paperclips, insects) to float on top without sinking.
Now, the paperclip isn’t actually floating- it is being held up by surface tension! By placing the paper towel on top of the water before the paperclip, you allow the water to form the “skin” which will be able to support the paperclip once it has sunk to the bottom.
What you’ll need
– 1 glass
– 2 paperclips
– 1 small piece of paper towel
What to do
– Fill your glass with water and gather your paper clips, paper towel and tooth pick.
– Grab 1 paper clip and place it on top of the water. Observe whether this floats or sinks.
(the paperclip will sink because surface tension hasn’t had a chance to build up on the surface)
– Grab your paper towel and gently float it on top of the water. Add your paperclip of top and you will see that it float. Give it a minute or two to sit and build a “skin” (surface tension).
– If your paper towel hasn’t sunk to the bottom on its own by now, pick up your toothpick and gently push the edges of the paper towel down. The paperclip will now float on top of the water.
– To break the surface tension of the water, grab your toothpick and poke the top of the water. The paperclip will float to the bottom.