Final answer:
A hand-operated device used to lift a vehicle is known as a jack, which can be a hydraulic or mechanical jack that uses lever systems to lift heavy loads.
Step-by-step explanation:
The hand-operated device used to lift and hold one corner or side of a vehicle is commonly known as a jack. In the context of heavy machinery and automotive use, this frequently refers to a hydraulic jack or sometimes a mechanical jack. These jacks leverage the principles of hydraulic and mechanical lever systems to lift substantial loads with minimal effort. A hydraulic jack, for example, consists of an incompressible fluid contained within a U-tube, which has a movable piston on each side. The narrower side of the U-tube allows for a small force applied over a small area to balance or lift a much larger force over a larger area. Similarly, a mechanical jack can employ a screw system that helps lift heavy objects with a mechanical advantage. The concept of these tools is rooted in the physics of levers, where forces are magnified by applying them at a distance from a pivot point.