An object and a concave mirror of focal length f = 10 cm both move along the principal axis of the mirror with constant speeds. The object moves with speed V₀ = 15 cm s⁻¹ towards the mirror with respect to a laboratory frame. The distance between the object and the mirror at a given moment is denoted by u. When u = 30 cm, the speed of the mirror Vₘ is such that the image is instantaneously at rest with respect to the laboratory frame, and the object forms a real image. The magnitude of Vₘ is_______cm s⁻¹.
Physics · Geometrical optics · spherical mirror
An object and a concave mirror of focal length f = 10 cm both move along the principal axis of the mirror with constant speeds. The object moves with speed V₀ = 15 cm s⁻¹ towards the mirror with respect to a laboratory frame. The distance between the object and the mirror at a given moment is denoted by u. When u = 30 cm, the speed of the mirror Vₘ is such that the image is instantaneously at rest with respect to the laboratory frame, and the object forms a real image. The magnitude of Vₘ is_______cm s⁻¹.
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