Question

knee flexion is an example of which class lever?
a) 1st
b) 2nd
c) 4th

Explanation:

In biomechanics (a subfield of Natural Science, specifically related to Biology/Medicine and Health), knee flexion involves the gastrocnemius and soleus muscles (effort) acting on the calcaneus, with the load (body weight) on the tibia and the fulcrum at the knee joint. A second - class lever has the load between the fulcrum and the effort. In knee flexion (for example, when standing on tiptoe which is related to knee - ankle mechanics), the load (body mass) is between the fulcrum (knee) and the effort (muscle force). First - class levers have fulcrum between load and effort, and there is no 4th - class lever in the standard three - class lever system. So knee flexion (in the context of lever systems in the body) is a 2nd - class lever.

Answer:

b) 2nd