Math 171 — Calculus I Spring 2016 Name: Weekly Write-Up on Sections 3.9-3.10 Problem 1. From the suggested homework: [3.10 #22] A laser pointer is placed on a platform that rotates at a rate of 20 revolutions per minute. The beam hits a wall 8 m away, producing a dot of light that moves horizontally along the wall. Let θ be the angle between the beam and the line through the searchlight perpendicular to the wall (see figure). How fast is this dot moving when θ = π/6? Problem 2. From an old exam: Use logarithmic differentiation to find dy x if y = xe . dx 1 2 Problem 3. For in-class discussion: A van is lifted into the air by a hydraulic jack for repairs. If the jack’s piston extends at a rate of 0.3 ft/sec, what is the upward velocity of the van when θ = 30◦ ?