Talk:Mechanical advantage

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It's easy to find sites with a mechanical advantage formula for 1st class levers, but it is not immediately obvious how to find mechanical advantage for 2nd and third class levers, other than 3rd class levers MA is less than one. This rule—mechanical advantage equals resistance divided by effort —applies to all machines A second class lever's mechanical advantage islike a first class lever's in that the distances are measured from the fulcrum and the MA is greater than 1.

Your arm is a third-class lever. It is this lever action that makes it possible for you to flex your arms so quickly. Your elbow is the fulcrum. Your biceps muscle, which ties onto your forearm about an inch below the elbow, applies the effort; your hand is the resistance, located about 18 inches from the fulcrum. In the split second it takes your biceps muscle to contract an inch, your hand has moved through an 18-inch arc. MA = 1/18 (less than 1)