Question

A double–threaded screw is made _____ revolutions. The pitch of the screw is 6 mm and the screw advanced to 6 cm.

(a) 6

(b) 5

(c) 7

(d) 4

The question was posed to me by my school principal while I was bunking the class.

The question is from Construction of Screw Threads topic in portion Curves used in Engineering Practice of Engineering Drawing

Answer 1

Correct option is (b) 5

The best explanation: Pitch of the screw is 6 mm given screw is double-threaded so for one revolution the screw advances to 6 mm x 2 = 12 mm. But the screw advanced to 6 cm = 60 mm. Number of revolutions = total screw advancement/ screw advancement for single revolution = 60 /12 = 5.