Question

which of the following requires the action of a first class lever in the body?
a. jumping
b. push - ups
c. waving
d. nodding

please select the best answer from the choices provided.
○ a
○ b
○ c
○ d

Explanation:

A first - class lever has the fulcrum between the effort and the load. When nodding, the atlanto - occipital joint acts as the fulcrum, the muscles at the back of the neck provide the effort, and the weight of the head is the load. Jumping mainly involves the use of leg muscles and the lever systems in the legs (which are second - class levers in many cases). Push - ups involve the arm and chest muscles with the elbow and shoulder joints, and the lever systems here are not first - class. Waving involves the arm and shoulder/elbow joints, and the lever systems are not first - class.

Answer:

D. nodding