In physics of road design, the phenomenon of raising the outer edge of a curved road above the inner edge to provide the necessary centripetal force for safe turning of vehicles is called:

Introduction / Context:
When vehicles move along a curved path, they require a centripetal force to keep them on the curve and prevent skidding outward or inward. Road engineers design curves so that part of this centripetal force comes from the normal reaction of the road surface, not only from friction. This is achieved by raising the outer edge of the road above the inner edge. The question asks for the standard term used in physics and road engineering for this design feature.

Given Data / Assumptions:

• The situation is a vehicle taking a turn on a curved road.
• The outer edge of the road is raised relative to the inner edge, creating an inclined surface.
• The options include terms such as banking, cornering, elevation, and tempering of roads.

Concept / Approach:
When a vehicle moves around a curve, it needs a centripetal force directed toward the centre of curvature. On a flat road, this force must be supplied entirely by the lateral friction between the tyres and the road. If the required centripetal force exceeds what friction can provide, the vehicle may skid. To reduce reliance on friction and improve safety, roads are often built with a slope or tilt, such that the surface is inclined at an angle to the horizontal. The outward edge is raised, and the inward edge is lower. This arrangement is called banking of roads. The normal reaction of the road on the vehicle then has a component toward the centre of curvature, providing part of the centripetal force. Terms like cornering and elevation are more general descriptive words and are not used as the specific technical term in this context. Tempering relates to heat treatment in materials and is not relevant to road geometry.

Step-by-Step Solution:

Verification / Alternative check:
Physics textbooks dealing with circular motion of vehicles devote a section to banked curves and derive expressions for the optimum banking angle at which a vehicle can negotiate a curve without relying on friction. They explicitly call this practice banking of roads. Engineering manuals on highway design talk about superelevation, which is the practical implementation of banking in road construction, again emphasising that the outer edge of the pavement is raised to counteract the outward tendency of vehicles. No standard reference uses cornering of roads or tempering of roads as technical names for this phenomenon.

Why Other Options Are Wrong:

Cornering of roads is wrong because it is not a technical term describing the raised edge design; it simply refers to turning at a corner.

Elevation of roads is incorrect as a specific term here; while roads do have an elevation above sea level, this does not describe the tilting of the road surface on curves to provide centripetal force.

Tempering of roads is clearly wrong because tempering is a metallurgical process used to treat metals, not a road design feature.

Common Pitfalls:
Students may confuse the common English word elevation with the technical concept of banking or may assume that any term mentioning a turn, such as cornering, is appropriate. Another pitfall is not connecting the physical concept of centripetal force to the specific engineering practice used to provide it. To answer correctly, remember that raising the outer edge of a curved road to help provide centripetal force is known as banking of roads.

Final Answer:
Hence, the phenomenon described is called banking of roads.