Question

A screw is said to be self locking screw, if its efficiency is

(a) less than 50%

(b) more than 50%

(c) equal to 50%

(d) none of the mentioned

The question was asked in a national level competition.

The origin of the question is Efficiency of Self Locking Screws topic in chapter Friction of Machine Kinematics

Answer 1

Correct option is (a) less than 50%

The explanation is: Efficiency of self locking screws is less than 1/2 or 50%. If the efficiency is more than 50%, then the screw is said to be overhauling.