Question

Open pairs are those which have

(a) point or line contact between the two elements when in motion

(b) surface contact between the two elements when in motion

(c) elements of pairs not held together mechanically

(d) two elements that permit relative motion

This question was posed to me in semester exam.

I'd like to ask this question from Grubler’s Criterion for Plane Mechanisms in division Simple Mechanisms of Machine Kinematics

Answer 1

Right option is (c) elements of pairs not held together mechanically

Easy explanation: Two elemets which are not held together form open pairs.

Two elements held together mechanically form a closed pair.