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Question about levers (Apologia General Science - Module 4)


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One of the "On Your Own Questions" (4.3) asks what class of levers tweezers belong to. The answer in the book says third class. I'm wondering if it matters what type of tweezers they are: the type that just have two long arms that you press in the middle to squeeze or the type that are more like scissors with two arms connected in the center by a screw (?) that you work by putting your thumb and forefinger through and push together. If you are thinking of the second kind, would that be a different class of levers?

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I've not seen the 2nd type you mention. If the force is in between the load and fulcrum, it is 3rd class as with eyebrow tweezers. If you are talking about something like a pair of scissors, the hinge is in the middle = class 1. The cutting surface of scissors is a wedge. Brownie

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Yes - I do believe that is right. It just depends what is in the middle. A wheelbarrow is 2nd class because the load is in the middle (versus the fulcrum or the force). Brownie

 

Thanks, Brownie. My son wrote 1st class because he was thinking of the scissors-type tweezers and the answer said 3rd class because it was referring to the other type. Not being particularly mechanically inclined I was perplexed. That's one of the things I like about homeschooling - I learn stuff too.:)

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