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How far is the football displaced from its original position?

  1. Dec 17, 2006 #1
    1. The problem statement, all variables and given/known data
    A quarterback takes the ball from the line of scrimmage and runs backwards for 1.0 x 10 ^1 m then sideways parallel to the line of scrimmage for 15 m. The ball is thrown forward 5.0 x 10^1 m perpendicular the line of scrimmage. The receiver is tackled immediately. How far is the football displaced from its original position?

    2. Relevant equations

    well I convert change the sci into 10m and 50m

    3. The attempt at a solution

    I don't know what kind of problem this is? what is it dealing with? yeah I'm looking for the displacement, but I thought displacement was just the difference from where it was at first... but well I have the answer which is 43m, but how in the world do I get to that number?

    and I'm so sorry for asking soo many questions, but I'm really lost and I have my mid term tomorrow. I know the rest but all these questions that I've been asking which were like mid through the semester. thanks to all who have been helping.
  2. jcsd
  3. Dec 17, 2006 #2


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    Homework Helper

    Drawing a sketch of the problem should help.
  4. Dec 17, 2006 #3
    because the ball goes at an angle from its original position, does it make sense that you could describe its final position as 40 meters forward and 15 meters to the right?
  5. Dec 17, 2006 #4
    I still don't get it... I don't know what equation to use...
  6. Dec 18, 2006 #5


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    Staff Emeritus
    Science Advisor

    Follow radou's hint: draw a diagram of the situation. Draw vectors representing each "stage" of the ball's journey. The total displacement will be the resultant vector.
  7. Dec 18, 2006 #6
    Heh, stop looking for an equation, the answer is right infront of you. :tongue:

    Take a piece of paper and as radou said, draw a diagram. Since the height of the ball doesn't matter, it is the exact same as this simplified problem.

    A man walks 10m backwards, then moves sideways 15m, then walks 50m forwards, how far is he from the original position? so basically you end up with a triangle with sides of 15m, and 40m, and a hypotenuse x which you need to find.

    Of course this can also be done with vector addition..

    edit::I would demonstrate the vector addition but I gotta go to bed. Here is something that should be at your level http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/vectors/u3l1b.html [Broken]
    Last edited by a moderator: May 2, 2017
  8. Dec 18, 2006 #7
    hehe thanks, I got it!
    thank y'all so much.
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