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Homework Help: Vector addition and motion diagram

  1. Apr 6, 2012 #1
    Mastering physics Knight. 2nd edition.
    A figure shows two dots of a motion diagram and vector [itex]\vec{V}_{1}[/itex] Copy this figure and add vector [itex]\vec{V}_{2}[/itex] and dot 3 if the accelration vector [itex]\vec{a}[/itex] at dot 2 (a) points up and (b) points down.

    [itex]\vec{V}_{1}[/itex] is a vertical vector pointing upward with two points, labelled 1 and 2. With 2 being the topmost point. The vector is 15 mm in length.

    The answer in the back of the book shows:
    a) Two vectors with a total of three points. They point up and a acceleration vector next to the second point which points down. The topmost vector is slightly shorter than the bottom one.
    b) Shows the same thing.

    I don't understand what's being asked or what there doing here.
    Last edited: Apr 6, 2012
  2. jcsd
  3. Apr 7, 2012 #2
    Are the dots supposed to represent position? I would guess that's the case for a motion diagram. It's been a while so I'm not 100% sure, though.

    But if that's the case, what can you say about the acceleration based off of what the position is at each dot (I also think with a motion diagram, each dot is separated by an equal amount of time, e.g. 1 dot every 1 second or something - again I'm not 100% sure, though. But that's needed in order to say something about velocity - which I'd assume is the vectors - well, average velocity)

    Hopefully someone else can chime in that is more confident.
    Last edited: Apr 7, 2012
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