31 March 2009

A different kind of strength

A weekend purge of my supplies cupboard (very therapeutic; thoroughly recommended!) turned up a forgotten supply of scritchy-scratchy sandpaper.  Which was crying out to be put to some use.

What could be better than to use it to test the strength of paper?  But hang on; haven’t we done that already?

Well, yes – and no.  Yes, we have found out the strength of paper.  But this is a different kind of strength.  This time we will be seeing how may times a strip of paper can be rubbed against a piece of sandpaper before it tears, or wears out.

Again we will test our familiar three kinds of paper; pink A4 writing paper, newspaper and paper towel.

Each strip of paper will be rubbed back and forth across a piece of sandpaper (which has been taped over a block of wood to make it easier to hold).

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A careful note will be made of the number of rubs needed to wear out each type of paper.


At the same time, a careful observation will be made of what happens to the paper as it is being rubbed across the sandpaper.  Look what happened to this piece of pink A4 paper:

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How was that different from what happened to the paper towel?

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And what about the newspaper?


Now ask yourself; did each group get the same results? 

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Why do you think this was?  Quentin told us that he and his group rubbed their strips of paper across the edge of the sandpaper block.  They rubbed really fast!  Their paper strips wore out after just a few rubs. 

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Tatiana and her group were still rubbing away when everyone else was finished.  They rubbed across the top of the sandpaper block and quite gently.


Now, I’m not sure about you, but I certainly know who to ask the next time I have any woodwork that needs sanding!

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