5.4 Starter 2 explained

5.4 Starter 2 explained

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Your finger pushes on the pin and the pin pushes back on your finger

·         N3L tells us that all these two forces are equal in size

·         The pin pushes on the wall and the wall pushes back on the pin

·         N3L tells us that all these two forces are also equal in size

·         If the surface area is large then the force is spread over a large area and the pressure is low

·         If the surface area is small then the force is spread over a small area and the pressure is high

·         You would like the pressure on your finger to be low and the pressure on the wall to be high

·         The other way round is painful!

animation - why a drawing pin works.swf Download this file