Thursday, July 1, 2010

Friction: Give Yourself a Hand

No surface is perfection smooth – they all have bumps of ridges to a various extent.

Friction occurs when two surfaces rub against each other and those bumps and ridges catch on each other.

A notable by-product of friction is heat.

Have your students rub their hands together quickly. It doesn’t take much hand rubbing to notice a warm feeling.

Now put a small squirt of lotion (stick to unscented stuff for this) in each students hand.

Have them rub their hands together again – much less heat is generated.

The lotion acts a lubricant – it helps fill in some of the bumps and ridges on the surface of the hands, resulting in less friction and therefore less heat.

Presented at the 2003 New Jersey Science Convention.

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