Results 1 to 3 of 3

Math Help - hard related rates problems..

  1. #1
    Newbie
    Joined
    Sep 2008
    Posts
    2

    hard related rates problems..

    hello guys! I've just registerd. I have some trouble in my calculus class.
    Would you please help me?
    These are the questions
    First question is not a related rate problem

    If y=f(w) and w=g(x), prove
    y''=(dy/dw)(dw/dx)+(dy/dw)(dw/dx)

    Second problem

    A guy is waking at the rate of 5 feet per second toward the spotlight which ison a post 20 feet above the ground. The guy is 6'2". Find the rate of change of the length of the guy's shadow at that exact moment when the guy is 24 feet away from the base of the post holding the spotlight.

    Thirdproblem

    Maple and Main streets are straight and perpendicular to each other. A
    stationary police car is located on Main Street, 1/4mile from the intersection of the two streets. A sports car, driven by Nasty Ry, approaches the intersection at the rate of 40 miles per hour. How fast is the distance between the two cars changing, and how is it changing, when the moving car is 1/8mile from the intersection.

    Please anwser my questions.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by moonyo91 View Post
    hello guys! I've just registerd. I have some trouble in my calculus class.
    Would you please help me?
    These are the questions
    First question is not a related rate problem

    If y=f(w) and w=g(x), prove
    y''=(dy/dw)(dw/dx)+(dy/dw)(dw/dx)
    note that y = f(g(x))

    now apply the chain rule twice. (you will have to apply the product rule the second time as well.

    Second problem

    A guy is waking at the rate of 5 feet per second toward the spotlight which ison a post 20 feet above the ground. The guy is 6'2". Find the rate of change of the length of the guy's shadow at that exact moment when the guy is 24 feet away from the base of the post holding the spotlight.

    Thirdproblem

    Maple and Main streets are straight and perpendicular to each other. A
    stationary police car is located on Main Street, 1/4mile from the intersection of the two streets. A sports car, driven by Nasty Ry, approaches the intersection at the rate of 40 miles per hour. How fast is the distance between the two cars changing, and how is it changing, when the moving car is 1/8mile from the intersection.

    Please anwser my questions.
    for these problems, did you draw a diagram? diagrams are essential for problems like these. draw the diagrams and see if they give you any ideas
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Sep 2008
    Posts
    2
    Yes but still struggling...
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. related rates problems..
    Posted in the Calculus Forum
    Replies: 10
    Last Post: August 30th 2010, 08:29 PM
  2. Problems with related rates
    Posted in the Calculus Forum
    Replies: 1
    Last Post: July 5th 2010, 02:08 PM
  3. hard related rates problem
    Posted in the Calculus Forum
    Replies: 2
    Last Post: October 24th 2009, 07:36 PM
  4. Related Rates problems
    Posted in the Calculus Forum
    Replies: 7
    Last Post: December 7th 2008, 03:18 AM
  5. Related Rates Problems (two)
    Posted in the Calculus Forum
    Replies: 1
    Last Post: November 2nd 2008, 09:37 AM

Search Tags


/mathhelpforum @mathhelpforum