Question

When the two elements of a pair have _____________ when in motion, it is said to a lower pair.

(a) line or point contact

(b) surface contact

(c) permit relative motion

(d) none of the mentioned

I got this question by my school teacher while I was bunking the class.

The doubt is from Kinematic Pair topic in chapter Simple Mechanisms of Machine Kinematics

Answer 1

The correct answer is (b) surface contact

The best I can explain: When the two elements of a pair have surface contact when relative motion, takes place and the surface of one element slides over the surface of the other, the pair formed is known as lower pair. It will be seen that sliding pairs, turning pairs and screw pairs form lower pairs.