Question

What is the proper relationship among the in-force, the out-force, and the fulcrum in a third class lever such as your elbow joint?

a) the fulcrum is positioned between the in-force and the out-force

b) the out-force is positioned between the in-force and the fulcrum

c) the in-force is positioned between the out-force and the fulcrum
d) the in-force is positioned directly above the fulcrum (there is no out-force)

e)the out-force is positioned directly below the fulcrum (there is no in-force)

Answer 1

Option C is the correct answer. There are three types of lever. First class of lever has its fulcrum placed between the applied force (in-force or effort) and the load (out-force). Examples include seesaw. In second class of lever, the load is placed between the fulcrum and the in-force. Examples include wheelbarrow. A third-class lever system has its in-force positioned between the load and fulcrum. Examples include most of the musculoskeletal levers of the human body.