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Thread: Vector addition

  1. #1
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    Vector addition


    Had this problem with vector addition don’t judge
    Question: find the sum of vector a and b
    Components of vA
    Sin30=x/15
    X=15*sin30=7.5
    Cos30=-y/15
    y=-12.9

    Components of vB
    Tan45=x/8
    X=8

    THIS IS THE PART I STALLED DUNNO HOW TO FIND Y COMPONENT OF vB below I have attached a diagram of how I did the question.

    Thanks

  2. #2
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    Re: Vector addition

    just to confirm your question is find (vector A + vector B)?

    it is good to see that you have had a go at the question first

    so let's break up the components of the vectors.

    for vector A, we can see that the it points straight down on the y axis. There is no X component of this vector.

    for vector B, we can use trig to resolve the vectors. the length of the Y component of Vb will be 15cos(30) = 12.99m and the X component of Vb will be 15sin(30) = 7.5m

    Your Y component for vector B has a negative for some reason. It would be best to take one direction of each axis as positive. So conventionally up on the y axis and to the right on the X axis are positive.

    Now what we do is add the X components of Vector A and Vector B together AND then the Y components of Vector A and Vector B together to get the resultant X and Y vector components.

    for X direction: 7.5m + 0m = 7.5m (note that there was no X component for vector B)

    for Y direction: -8m + 12.99m = 4.99m (-8m because the vector is pointing down)

    So the resultant vector will look like this (in green):



    so the final answer would be:

    the resultant vector is of length 4.99 units at 33.69 degrees CCW from the positive X axis
    Last edited by Squar3root; 19 Mar 2019 at 8:55 PM.
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