A laser pointer at point emits a beam along the positive axis

PHYSICS · Multi-part · ISC · Physics · Kinematics · Kinematics

Problem

A laser pointer at point P(0,0,0)P(0,0,0) emits a beam along the positive xx axis. A small, square mirror is located at point M(1.0,0,0)M(1.0,0,0) and is free to rotate about both the yy (pitch) and zz (yaw) axes. The goal is to reflect the beam so that it hits a target on the laboratory ceiling at point T(1.0,2.0,3.0)T(1.0,2.0,3.0) (coordinates in metres). (a) Write the condition that must be satisfied by the mirror’s unit normal vector n\mathbf{n} so that an incident ray from PP reflects into a ray toward TT. Express your condition symbolically in terms of n\mathbf{n} and the incident and desired reflected direction vectors. (b) Solve for a unit normal vector n\mathbf{n} that meets the requirement in part (a). Show all steps leading to your final numerical components for n\mathbf{n}. (c) From the components of n\mathbf{n} found in part (b), determine the pitch (rotation about the yy axis) and yaw (rotation about the zz axis) angles the mirror must execute, taking the mirror’s unrotated surface to lie in the yzyz plane. State each angle to the nearest tenth of a degree. (d) Briefly explain how the required pitch would change if the target point were moved farther away in the +x+x direction while keeping its yy and zz coordinates the same.

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