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Homework Help: Unit Vector Notation help?

  1. Sep 27, 2013 #1
    1. The problem statement, all variables and given/known data
    A steel ball is fired from a ballistic launcher at different angles. The launched ball has been found to travel from the edge of a table to land 30.0 cm from the far end of the table when starting from the height of the table and launched at an angle of 30.0◦ above the horizontal. When launched at 45.0◦ , the ball easily clears the table to land on the floor.
    Letting the edge of the table from which the ball was launched have coordinates (x(0),y(0))=(0,0), write an expression for the x and y components of the object’s position vector. Next, write an expression for the full position vector.
    I am trying to figure out how to write this expression. Underneath this explanation on my sheet I have a rx,30◦=x30◦=______, and a ry,30◦=y30◦=_______ and below that r(with -> on top)30◦(t)=______. I am confused as to write this, including the i-hats and j-hats unit vectors.

    2. Relevant equations


    3. The attempt at a solution

    I understand the break down such as A = Ax + Ay = Axi + Ayj and so on, but where to put the numbers 0 and such are confusing me. I hope this format is correct for the forum!
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution

    Attached Files:

  2. jcsd
  3. Sep 27, 2013 #2


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    Staff: Mentor

    First write the expression in x, then in y, then combine both using ##\hat{\imath}## and ##\hat{\jmath}##.

    If you start with the individual components, you won't have to worry aobut the zeros. But you can also write a zero as ##0\hat{\imath} + 0\hat{\jmath}##.
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