Recent content by ktobrien

  1. K

    Using Symmetry to Evaluate Double Integrals over a Square Region

    SS_D 6 is 300 over the square. x goes from 0 to 5 and y goes from x-5 to 5-x. This is half of the square. This integral equals 150. You then multiply that by 2 to get the whole square. The answer is therefore 300. My answer is correct. Also, D is not a 10X10 square. It is a 5X5 square...
  2. K

    Using Symmetry to Evaluate Double Integrals over a Square Region

    Yes. SS_D 6 is also 300. Does this mean my answer is right?
  3. K

    Using Symmetry to Evaluate Double Integrals over a Square Region

    Homework Statement Use symmetry to evaluate the given integral. SS_D 6-x+7y dA where D is the region bounded by the square with vertices (±5, 0) and (0, ±5). Homework Equations Integrals The Attempt at a Solution I worked it out and got 300. But I did it by integrating one half then the other...
  4. K

    How Can Engineers Design a Temperature-Independent Resistor?

    Plugging into the two formulas I got. 3.5e-5(l1) + 1.5e-6(l2) = 9.2363e-5 but this gives me 1 equation and 2 unknowns
  5. K

    How Can Engineers Design a Temperature-Independent Resistor?

    Rho is the resistivity. Alpha is the temperature coefficient. Both values of resistivity are positive as written. Carbons temperature coefficient is positive and nichromes is negative.
  6. K

    How Can Engineers Design a Temperature-Independent Resistor?

    Homework Statement An engineer needs a resistor with zero overall temperature coefficient of resistance at 20°C. She designs a pair of circular cylinders, one of carbon and one of Nichrome. The device must have an overall resistance of R1 + R2 = 15.0 Ω independent of temperature and a...
  7. K

    Finding Tangent Plane and Normal Line Equations for a Given Surface

    Ive got it now. I used the linear approximation and set it = to 0. I just had to take out the f(5,3,-3). I figured it was something stupid like that. Thanks for the help though.
  8. K

    Finding Tangent Plane and Normal Line Equations for a Given Surface

    Homework Statement Find equations of the following. x2-2y2+z2+yz=7, (5,3,-3) (a) the tangent plane (b) the normal line to the given surface at the point Homework Equations I know it involves fx, fy, fz The Attempt at a Solution I got 10x-15y-3z=7. Is this correct? Because its not true at...
  9. K

    Directional Derivatives and the Gradient Vector

    Yea that's what I thought. Thanks for confirming that. I just discovered my calculator has been in radians. Thanks.
  10. K

    Directional Derivatives and the Gradient Vector

    Homework Statement Suppose you are climbing a hill whose shape is given by the equation below, where x, y, and z are measured in meters, and you are standing at a point with coordinates (120, 80, 1064). The positive x-axis points east and the positive y-axis points north. z = 1200 - 0.005x2...
  11. K

    Partial Derivatives and The Chain Rule

    Thanks a lot. I figured it was something simple like that.
  12. K

    Partial Derivatives and The Chain Rule

    No the other ones are right. I have already checked them. How do I get L to know what to divide by? Do I just plug in the original l w h to find L?
  13. K

    Partial Derivatives and The Chain Rule

    2l(dl/dt)+2w(dw/dt)+2h(dh/dt) for A I got 675m^3/s for B I got 312m^2/s
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