Section 3.8-solutions-1

Section 3.8-solutions-1 - to (aqt73) – Section 3.8 –...

This preview shows pages 1–2. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: to (aqt73) – Section 3.8 – isaacson – (55826) 1 This print-out should have 5 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points A rock is thrown into a still pond and causes a circular ripple. If the radius of the ripple is increasing at a rate of 6 ft/sec, at what speed is the area of the ripple increasing when its radius is 2 feet? 1. speed = 24 sq. ft/sec 2. speed = 23 sq. ft/sec 3. speed = 23 π sq. ft/sec 4. speed = 25 sq. ft/sec 5. speed = 21 π sq. ft/sec 6. speed = 21 sq. ft/sec 7. speed = 22 π sq. ft/sec 8. speed = 24 π sq. ft/sec correct Explanation: The area, A , of a circle having radius r is given by A = πr 2 . Differentiating implicitly with respect to t we thus see that dA dt = 2 πr dr dt . When r = 2 , dr dt = 6 , therefore, the speed at which the area of the ripple is increasing is given by speed = 24 π sq. ft/sec . 002 10.0 points A street light is on top of a 10 foot pole....
View Full Document

This note was uploaded on 06/14/2011 for the course MATH 305G taught by Professor Cathy during the Spring '11 term at University of Texas.

Page1 / 3

Section 3.8-solutions-1 - to (aqt73) – Section 3.8 –...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online