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◦ ?