Although humans have long wondered about the origin of knowledge, the actual field of psychology did not come into existence until the late 1800’s because:

Shafts are machine elements that are used to a) carry axial loads b) direct shear loads c) transmit power d) rotate at constant speed e) none of the above circular and square shafts subjected to the same torque under the same circum behave a) the same way b) almost the same way