Recent content by KV-1

  1. K

    Calculating maximum shear in a steel beam cantilever

    Problem: I do not know how to approach this problem. For a beam which has two reactions, the shear stress is equivalent to the reaction. I suppose that the stress is calculated using moment some how. But how? For seeing if the beam is allowable stress design compliant, you can use the...
  2. K

    Calculating size of wooden members

    I found out this is commonly done using several rules of thumb, feel free to ask about them in this thread
  3. K

    Calculating size of wooden members

    I need help calculating the size of the wood members I need in my truss. I understand the basics; I first need to calculate the load, then the stress on each member, then pick a wooden member which has that stress with a safety factor of let's say 2.0. The reason why I want to perform the...
  4. K

    UnitDeadLoad.htm What is unit dead load and how does it differ from unit weight?

    What is the difference between the unit dead load and the unit weight of a material? For example, the unit weight for structural concrete is 145lb/ft^3. What would the unit dead load be? 145lb?
  5. K

    Vertical Load on a Purlin - find x and y force components

    A roof purlin, supported by a roof rafter must support a 300 lb vertical snow load. Determine the component of of the snow load as a concentrated load “P” both perpendicular and parallel to the axis of the rafter. I read that the perpendicular component of the 300lb force can be figured out by...
  6. K

    Can Multivariable Interpolation Relate Three Sets of Data Points?

    Oh thanks! Not sure though, I think I found some equations that give me the desired points without having to interpolate though... It helps to know how this can be done though!
  7. K

    Can Multivariable Interpolation Relate Three Sets of Data Points?

    Hello! I am wondering if it is possible to establish a relationship between three sets of points (x,y,z) by interpolating. Basically i need a function that takes x and y and gives me a z that matches the following points: 130 472 5 130...
  8. K

    Interpolation help fitting curve to three points

    Hello, I have the following points that need to be fitted with a curve: (1,20);(2,4);(5,3) I'm wondering how to use the http://en.wikipedia.org/wiki/Lagrange_polynomial to do this. If possible, can these points be fitted with a cubic function? I tried to fit a cubic to this, but...
  9. K

    Derivatives of ln including Absolute Value

    Nope, no separate derivatives needed. I don't remember the proof, but if its a natural log involving an absolute value, the derivative would be the same for f(x) if abs() wasn't there. Do you want me to find it? Also.. why are you factoring things? Just use the chain rule. d/dx (ln|w|) =...
  10. K

    Solve Limit arctg (x) - Get Help Now

    Jalo , use google! https://www.physicsforums.com/showthread.php?t=153587 =P same problem as you
  11. K

    How Do You Divide a Dome into Equal Pie-Shaped Sections for a Mural?

    A little late, But this might help those struggling with the same problem. Use a dymaxion map--simplify a sphere into a polyhedron: http://en.wikipedia.org/wiki/Dymaxion_map http://upload.wikimedia.org/wikipedia/commons/b/bb/Dymaxion_2003_animation_small1.gif and then transfer...
  12. K

    Quick Question differentiating logs

    ((-0.76)(log(e)))/((-0.76x+305)(log(1.5)) thats the answer i think... in case anyone is curious
  13. K

    Quick Question differentiating logs

    yes, but there seems to be truly no need for the chain rule, as log(1.5) is a number, equal to 0.176091 so it seems i just multiply the derivative of [log base 10 (-0.76x+305)] by that number!
  14. K

    Quick Question differentiating logs

    1. my function is: f(x)=log 1.5 (-.76x+305). f(x)= log base 1.5 of -.76x+305 3. How do i differentiate it? here is what i have so far: (1/((-.76x+305)ln1.5))*(-.76/dx)
  15. K

    Why Does My Ellipse Tangent Calculation Lead to Infinity?

    Hah, It's actually (b^2-a^2)/b for the answer... don't know why, but the y-mx+b yielded the correct answer... less room for mistakes there! thanks a lot though Mark44
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