Question

list the 3 classes of levers, their function, and a muscle example for each and name the axis resistance and force in each example.
- for the first class lever the example cant be nodding the head.
-no full body push up examples.
-no tricep or bicep examples.

Answer 1

There are three classes of levers, identified as first, second, and third class
levers. In a first class lever, the weight and force are on opposite sides of the fulcrum. A small force can be used to advantage over a heavy weight if along force arm or lever arm can be used. Examples of this lever include scissors, crowbars, and
teeter-totters.


In the second class lever, the load is between the fulcrum and the force. A smaller effort can be used to advantage over a larger weight. An exampleof
this lever is a wheelbarrow. An example in the human body of a second-class lever is the Achilles tendon, pushing or pulling across the heel of thefoot.


In the third class lever, the force is between the fulcrum and the load. In this case, there is no force advantage – force is NOT increased. In fact,a
larger force is actually needed to move a smaller weight, so there is a force
disadvantage. The use of this lever is in the gain in speed of movement of the
weight.
Examples of this lever class include: The inside door handle of a car, the coiled
spring pulling on a screen door, a pair of finger-nail clippers, and tweezers.
An example of a third-class lever in the human body is the elbow joint: when
lifting a book, the elbow joint is the fulcrum across which the biceps muscle
performs the work.