Final answer:
Convex mirrors in vehicles make cars appear smaller and provide a wider field of view compared to flat mirrors, but the distortion in size can lead to misjudgment of distance. The phrase 'Objects in mirror are closer than they appear' identifies the use of a convex mirror. An experiment with a straight object can confirm the convex shape of the mirror.
Step-by-step explanation:
Convex mirrors make cars seem smaller than they really are and provide a broader view of the roadway than do flat mirrors. Convex mirrors are also known as diverging mirrors because they cause light rays to spread out, or diverge. This divergence allows the mirrors to create an image that encompasses a wider field of view, which is why they are advantageous for use in vehicles.
The main disadvantage of using a convex rearview mirror compared to a flat one is that it distorts the size of objects, making them appear smaller and therefore potentially farther away than they are in reality. This can sometimes be a safety concern for drivers who may misjudge the distance of vehicles behind them.
A well-known warning phrase that can often be found on such mirrors is 'Objects in mirror are closer than they appear', confirming the use of a convex mirror. To experimentally determine the shape of the mirror, one could perform a simple visual test, observing how the reflection of a straight object, such as a ruler, appears curved when placed against the mirror's surface, indicating its convex nature.