By doing so, weld current and force is focused into the small area of the projection, and heat is obtained from the resistance to the flow of the welding current. Due to this heat, the projections collapse and the parts are weld together. Another successful welding technique is capacitor discharge stud welding, which uses weld studs or specially formed bolts for welding instead of projections.
Definition of inert. 1  1 : lacking the power to move. 2  2 : very slow to move or act : sluggish. 3  3 : deficient in active properties; especially : lacking a usual or anticipated chemical or biological action.
Inertia is a word we use when we talk about matter and movement. Basically, our idea of inertia goes back to Sir Issac Newton's first two laws of physics: 1. An object at rest tends to stay at rest. 2. An object in motion tends to stay in motion.