Recent content by jimvoit

  1. J

    How Do I Correctly Calculate Vector C Using Unit Vectors?

    If angles are measured positive counter-clockwise from the positive x-axis (as standard) then your value for B is incorrect.
  2. J

    Understanding the Quotient Rule for Derivatives of 3/x^2

    Instead of using the quotient rule, you might find it easier to evaluate 3 x^-2
  3. J

    Unit Vectors with No Scalar

    You have been given that i and j are directed to the east and north. This follows the standard convention for a 2D Cartesian coordinate system in which i and j are directed along the positive x and y-axis respectively. In this system, a unit vector with a direction alpha, measured...
  4. J

    Vector - points in same direction

    It is a good idea to make carefull use of parentheses so that there is no ambiguity as to the meaning of an expression. Consider that for positive constants k, and vectors v, k v is in the same direction of v.
  5. J

    Vector Motion Problems: Finding Direction and Speed of a Plane

    This might also help you with these kind of problems: You have three vectors a, b, c: The wind velocity a=(a1,a2) The velocity of the airplane through the air b=(b1,b2) The velocity of the airplane along the ground c=(c1,c2) The...
  6. J

    Mathematical notation outdated?

    You might be interested in the paper: Mathematical Notation: Past and Future (2000). Stephen Wolfram October 20, 2000.
  7. J

    Estimate Diameter of Moon Using Pencil Measurements

    Your also need to also estimate the distance from your eye to the pencil. Draw a picture...there are two similar triangles involved
  8. J

    Finding Angle of Vectors in 2D Space

    Two vectors have a magnitude of 86.4 and an x coomponent of 62.3: In the first quadrant (62,3, 59.9) In the fourth quadrant (62.3, -59.9) Their polar coordinates are: In the first quadrant (86.4, 43.86 degrees) In the fourth quadrant (86.4, -43.86 degrees)
  9. J

    How Does Newton's Third Law Apply to Forces in an Elevator?

    What would be the force on the mans feet if he and the elevator were in free fall? Zero ?
  10. J

    Finding Angles in Tool and Die Mathematics Questions

    The cut and paste did'nt work too well, but if you let the small square be the symbol for angle, then my results are: afe=156; cde=140; ed=60; 2=afe/2; 1=90-2; 3=1; 4=90; 7=ed/2; bc=180-cde; 6=bc/2; 9=180-6-7; 10=180-9; 5=90-10; 8=90-5-6; 1,2, 3, 4, 5...
  11. J

    Finding Angles in Tool and Die Mathematics Questions

    I should have said arc AFE. It's clear in the thumbnail sketch that its arc AFE, arc CDE and arc ED that they are talking about because they use the "hat" symbol above the letters. In any future posts I'll make sure I'm clear about whether its angles or arcs I'm talking about.
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    Finding Angles in Tool and Die Mathematics Questions

    Correct above post to read "AFE is ..."
  13. J

    Finding Angles in Tool and Die Mathematics Questions

    AFC is 156 degrees. The symmetry of the construction indicates that angle_2 is half that. (78 degrees). Since OAP is a right triangle, angle_1 is 90-Angle_2. (12 degrees)
  14. J

    Finding Angles in Tool and Die Mathematics Questions

    angle 1 = 90 - angle 2 = 90 - (156/2) = 12 This may be incorrect, but if the drawing is to scale then angle 1 is not 66 degrees.
  15. J

    Parentheses or brackets (US/UK terminology question)

    The computer algebra system Mathematica uses the term "Bracketing" in the following way: Four kinds of bracketing: (term) parenthesis for grouping f[x] square brackets for functions {a,b,c} curly braces for lists v[[i]] double brackets for indexing Notice that "bracket" is...
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