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Help me !

  1. Sep 25, 2004 #1
    help me plz!

    Im very rusty heres my problem, please help thanks!

    The radius of a sphere is expanding at the rate of 1 meter/min. At t=0 the radius is 1. In earch case, find the requested function and sketch the curve.

    a)The surface area of the sphere as a function of the time;
    For this i took: dR/dt = 1 m/min
    A=4*Pi*r^2
    dA/dt=8*pi*r*dR/dt
    dA/dt = 8*pi*r <--- if this is right how do i sketch this graph as a function of time??
    my graph points that i ploted were (0,8pi),(1,16pi),(2,24pi) etc... but this is confusing me because at t=0 radius is 1... is my x-axis supposed to be time or radius someone help me im confused..
     
  2. jcsd
  3. Sep 25, 2004 #2

    Tide

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    Write r as a function of time then plot:
    [tex]r = 1 + t[/tex]
     
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