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Math Help - Work done (Question on Vectors)

  1. #1
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    Work done (Question on Vectors)

    Can someone help me with this one, please.

    Find the work done by a two dimensional force of 2[units] in the direction of the line y= (3x-3)(upward) in moving an object from point Q=(1,-2,-3) to point P=(-1,0,1).
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  2. #2
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    Quote Originally Posted by Tron View Post
    Can someone help me with this one, please.

    Find the work done by a two dimensional force of 2[units] in the direction of the line y= (3x-3)(upward) in moving an object from point Q=(1,-2,-3) to point P=(-1,0,1).
    displacement vector \vec{QP} = -2i + 2j + 4k

    force vector \vec{F} = \frac{2}{\sqrt{10}}i  + \frac{6}{\sqrt{10}}j

    determine the scalar product of the two vectors
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  3. #3
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    Quote Originally Posted by skeeter View Post
    displacement vector \vec{QP} = -2i + 2j + 4k

    force vector \vec{F} = \frac{2}{\sqrt{10}}i  + \frac{6}{\sqrt{10}}j

    determine the scalar product of the two vectors
    Thx a lot

    How did you calculate the force vector?
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  4. #4
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    Quote Originally Posted by Tron View Post
    Thx a lot

    How did you calculate the force vector?
    I picked two points on the line ... (0,-3) and (1,0)

    direction of the force vector is ...

    i + 3j

    unit vector in that direction is ...

    \frac{i+3j}{\sqrt{1^2 + 3^2}}

    finally, multiply the unit vector by the magnitude of F.
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