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Slippery Slopes and Sticking Surfaces: Exploring the Forces of Friction

Postby KendraBowen » Mon Oct 22, 2018 11:39 am

Hi! This project greatly interested my son for his science fair project. However, we are not allowed to use human subjects. This is fine, as we have decided to use a sand bag as a replacement for the human subject. What force will we be using? Gravity? We cannot push the bag down the slide, as we could not consistently give the same amount of force each testing. How could we even measure this to give results that can be easily tabulated? Thank you so much for your help!

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Re: Slippery Slopes and Sticking Surfaces: Exploring the Forces of Friction

Postby norman40 » Wed Oct 24, 2018 3:57 pm

Hi Kendra,

You need to give the sand bag a shove to get it started down the slide. And it may be a little difficult to do this consistently. It may help to start the sand bag on the sloped part of the slide instead of the horizontal section at the top. That way, a less forceful shove will be needed to get the sand bag moving.

The timed runs down the slide (step 2b in the project procedure) can give you an indication of the consistency of your starting shove. If you find that ten trials show very similar times down the slide then your start is consistent. My suggestion is to mark put marks on the slide near the top and bottom. Start your timer when the sand bag passes the top mark and stop it when the bag passes the bottom mark.

I hope this helps. Please ask again if you have more questions.

A. Norman

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