Results 1 to 3 of 3

Math Help - Temperature

  1. #1
    Junior Member
    Joined
    Mar 2009
    Posts
    42

    Temperature

    The late Mac the Knife is found at midnight with a body temperature of 90 degrees F, in a room where the temperature is 70.
    At 1 a.m. he has cooled to 80 degrees.

    When was he killed? Why?

    Can this equation get me to the answer?

    89 = 70 +20e^{-0.01t}
    Last edited by cammywhite; May 2nd 2009 at 05:50 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie
    Joined
    May 2009
    Posts
    7
    Is that all that was given to you? The question seems to be very confusing. Your equation is right but -.01 shouldn't be there btw, you need to use Newton's law of cooling which states that if u is the object then the rate at which it cools is

    du/dt = -k(u - T)

    -k = constant

    T = ambient temperature
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by cammywhite View Post
    The late Mac the Knife is found at midnight with a body temperature of 90 degrees F, in a room where the temperature is 70.
    At 1 a.m. he has cooled to 80 degrees.

    When was he killed? Why?

    Can this equation get me to the answer?

    89 = 70 +20e^{-0.01t}
    You need to solve the differential equation (Newton's law of Cooling) given in post #2. Let t = 0 correspond to midnight. Then the boundary conditions for this differential equation are T = 90 degrees F at t = 0 and T = 80 degrees F at t = 1.

    You need to find the value of t (it will be negative) when T = 98.9 degrees F (normal temperature of living person).
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Temperature
    Posted in the Calculus Forum
    Replies: 1
    Last Post: December 6th 2009, 06:50 PM
  2. temperature
    Posted in the Algebra Forum
    Replies: 2
    Last Post: November 30th 2009, 06:07 PM
  3. temperature PDE
    Posted in the Differential Equations Forum
    Replies: 1
    Last Post: February 9th 2009, 08:32 PM
  4. Temperature
    Posted in the Calculus Forum
    Replies: 1
    Last Post: January 3rd 2009, 09:37 AM
  5. Temperature
    Posted in the Math Topics Forum
    Replies: 2
    Last Post: February 11th 2007, 06:17 AM

Search Tags


/mathhelpforum @mathhelpforum