November 9th, 2017, 01:43 PM  #1 
Newbie Joined: Nov 2017 From: Canada Posts: 4 Thanks: 0  Related rates  bridge / boat
A bridge goes across the river at a height of 60m. A car on the bridge travelling at 40 m/s passes directly over a boat travelling up the river at 15 m/s. Find the rate at which the distance between the car and the boat is increasing 3 seconds later?

November 10th, 2017, 03:24 AM  #2 
Math Team Joined: Jan 2015 From: Alabama Posts: 2,976 Thanks: 807 
One method: set up a coordinate system so that (0, 0, 0) is the position of the boat directly under the bridge and (0, 0, 60) is the position of the car with the xaxis parallel to the bridge. What are the positions of the boat and car t seconds later? What is the distance between those two points? Differentiate that formula with respect to t to find the rate of change of that distance.


Tags 
boat, bridge, rates, related 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Related Rates  kagami08  Calculus  1  October 5th, 2015 04:07 PM 
An algebra word problem on rates concerning a boat  Lambin  Algebra  2  January 3rd, 2013 05:38 PM 
related rates  kfarnan  Calculus  2  October 13th, 2011 03:18 PM 
related rates  rcstrick  Calculus  1  March 3rd, 2009 12:28 AM 
and another related rates  rcstrick  Calculus  1  March 3rd, 2009 12:17 AM 