Final answer:
The mirror discussion relates to the Physics of optics, where the placement height for a mirror to view oneself is generally half a person's height, and the focal length of a concave mirror with specific image properties is -10 cm.
Step-by-step explanation:
The question pertains to the height placement of mirrors, which is a topic covered in Physics specifically in discussions about optics and the properties of mirrors. For example, to see one's entire body in a flat mirror, the height of the mirror should be half the height of the person, irrespective of the distance from the mirror. This is due to the way angles of incidence and reflection work; the top and bottom of one's body form angles with the mirror that allow a person to see their full reflection when the mirror is half their height.
Regarding the mirror's focal length question, based on the property that an upright image is formed and is twice as large as the object, and given the object's distance is 10 cm, one can use the mirror equation to determine that the focal length of such a mirror would be -10 cm, indicating it's a concave mirror.