lever systems Flashcards
what is a lever?
any rigid segment that rotates around a fulcrum
what does the quick acronym F.R.E stand for!
1st class lever: fulcrum in the middle
2nd class lever: resistance in the middle
3rd class lever: effort in the middle
what is always acts as the effort force in the lever systems?
the muscle contracting
tilting the head back
first class lever
raising heel off ground
second class lever
flexing elbow
third class lever
what is acting as the effort in a first class lever of tilting the head back?
the neck extensors contracting
what is acting as the effort force in a second class lever of the heels raising off the ground?
the gastrocnemius muscle contracting
what is acting as the effort force in a third class lever of the elbow flexing?
the biceps contracting
what kind of lever system would most muscle contractions be?
2nd and 3rd class levers
what is the efficiency of the lever determined by?
the lengths of the lever arms
what is the equation for mechanical advantage?
(MAd) = EA/RA
if EA is >RA, then mechanical advantage is (> , < ,or =) to 1
> 1
if EA is > RA, then what does this mean?
it requires less effort to move the lever
what is MAd (mechanical advantage) for second class levers? and what does this mean for EF and angular displacement
> 1; smaller effort force is required but less angular displacement and velocity is gained
what is MAd for 1st and 3rd class levers? and what does this mean for EF and angular displacement
MAd < 1; larger EF required but MORE angular displacement and velocity is gained
