Polytechnic Interview Q&A — 24 branches, 480 interview questions. Click a branch to see its 20 Q&A. Mechanical Engineering 20 Q&A Q1. What is Mechanical Engineering? Mechanical Engineering is the branch that deals with the design, manufacturing, and maintenance of mechanical systems, covering areas like thermodynamics, machine design, manufacturing processes, and fluid mechanics. Q2. What is the difference between stress and strain? Stress is the internal resisting force per unit area developed inside a material when an external load is applied, while strain is the resulting deformation (change in length or shape) per unit original dimension caused by that stress. Q3. What is the difference between a two-stroke and four-stroke engine? A two-stroke engine completes a power cycle in one crankshaft revolution (two piston strokes), while a four-stroke engine takes two revolutions (four strokes: intake, compression, power, exhaust); four-stroke engines are more fuel effi...