Topic: Theory of Machines
Which of the following is a lower pair?
- A. Piston and cylinder
- B. Cam and follower
- C. Belt drive
- D. Gear
Answer: A. Piston and cylinder
Explanation: When two elements of a pair are joined together with surface contact between them, the joint is called a lower pair. Prismatic pair (piston and cylinder), spherical pair (Ball and socket), screw pair etc. are examples of lower pairs.